Impedance detect drive sense circuit

ABSTRACT

A drive-sense circuit coupled to a variable impedance load. The drive-sense circuit includes a voltage reference circuit operable to generate a voltage reference signal. The drive-sense circuit further includes a regulated current source circuit operable to generate a regulated current signal based on an analog regulation signal, where the regulated current signal is provided on a line to the variable impedance load to keep a load voltage on the line substantially matching the voltage reference signal, and where an impedance of the variable impedance load affects the regulated current signal. The drive-sense circuit further includes a current loop correction circuit operable to generate a comparison signal based on the voltage reference signal and the load voltage, where the comparison signal represents the impedance, and where the analog regulation signal is representative of the comparison signal.

CROSS REFERENCE TO RELATED APPLICATION

The present U.S. Utility Patent Application claims priority pursuant to35 U.S.C. § 120 as a continuation-in-part of U.S. Utility applicationSer. No. 16/113,379, entitled “DRIVE SENSE CIRCUIT WITH DRIVE-SENSELINE,” filed Aug. 27, 2018, which is hereby incorporated herein byreference in its entirety and made part of the present U.S. UtilityPatent Application for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not Applicable.

BACKGROUND OF THE INVENTION Technical Field of the Invention

This invention relates generally to data communication systems and moreparticularly to sensed data collection and/or communication.

Description of Related Art

Sensors are used in a wide variety of applications ranging from in-homeautomation, to industrial systems, to health care, to transportation,and so on. For example, sensors are placed in bodies, automobiles,airplanes, boats, ships, trucks, motorcycles, cell phones, televisions,touch-screens, industrial plants, appliances, motors, checkout counters,etc. for the variety of applications.

In general, a sensor converts a physical quantity into an electrical oroptical signal. For example, a sensor converts a physical phenomenon,such as a biological condition, a chemical condition, an electriccondition, an electromagnetic condition, a temperature, a magneticcondition, mechanical motion (position, velocity, acceleration, force,pressure), an optical condition, and/or a radioactivity condition, intoan electrical signal.

A sensor includes a transducer, which functions to convert one form ofenergy (e.g., force) into another form of energy (e.g., electricalsignal). There are a variety of transducers to support the variousapplications of sensors. For example, a transducer is capacitor, apiezoelectric transducer, a piezoresistive transducer, a thermaltransducer, a thermal-couple, a photoconductive transducer such as aphotoresistor, a photodiode, and/or phototransistor.

A sensor circuit is coupled to a sensor to provide the sensor with powerand to receive the signal representing the physical phenomenon from thesensor. The sensor circuit includes at least three electricalconnections to the sensor: one for a power supply; another for a commonvoltage reference (e.g., ground); and a third for receiving the signalrepresenting the physical phenomenon. The signal representing thephysical phenomenon will vary from the power supply voltage to ground asthe physical phenomenon changes from one extreme to another (for therange of sensing the physical phenomenon).

The sensor circuits provide the received sensor signals to one or morecomputing devices for processing. A computing device is known tocommunicate data, process data, and/or store data. The computing devicemay be a cellular phone, a laptop, a tablet, a personal computer (PC), awork station, a video game device, a server, and/or a data center thatsupport millions of web searches, stock trades, or on-line purchasesevery hour.

The computing device processes the sensor signals for a variety ofapplications. For example, the computing device processes sensor signalsto determine temperatures of a variety of items in a refrigerated truckduring transit. As another example, the computing device processes thesensor signals to determine a touch on a touch screen. As yet anotherexample, the computing device processes the sensor signals to determinevarious data points in a production line of a product.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic block diagram of an embodiment of a communicationsystem in accordance with the present invention;

FIG. 2 is a schematic block diagram of an embodiment of a computingdevice in accordance with the present invention;

FIG. 3 is a schematic block diagram of another embodiment of a computingdevice in accordance with the present invention;

FIG. 4 is a schematic block diagram of another embodiment of a computingdevice in accordance with the present invention;

FIG. 5A is a schematic plot diagram of a computing subsystem inaccordance with the present invention;

FIG. 5B is a schematic block diagram of another embodiment of acomputing subsystem in accordance with the present invention;

FIG. 5C is a schematic block diagram of another embodiment of acomputing subsystem in accordance with the present invention;

FIG. 5D is a schematic block diagram of another embodiment of acomputing subsystem in accordance with the present invention;

FIG. 5E is a schematic block diagram of another embodiment of acomputing subsystem in accordance with the present invention;

FIG. 6 is a schematic block diagram of an embodiment of a drive sensecircuit in accordance with the present invention;

FIG. 6A is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 7 is an example of a power signal graph in accordance with thepresent invention;

FIG. 8 is an example of a sensor graph in accordance with the presentinvention;

FIG. 9 is a schematic block diagram of another example of a power signalgraph in accordance with the present invention;

FIG. 10 is a schematic block diagram of another example of a powersignal graph in accordance with the present invention;

FIG. 11 is a schematic block diagram of another example of a powersignal graph in accordance with the present invention;

FIG. 11A is a schematic block diagram of another example of a powersignal graph in accordance with the present invention;

FIG. 12 is a schematic block diagram of an embodiment of a power signalchange detection circuit in accordance with the present invention;

FIG. 13 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 14 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 15 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 16 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 17 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 18 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 19 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 20 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 21 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 22 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 23 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 24 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 25 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 26 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 26A is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 27 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 28 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 29 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 30 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 30A is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 31 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 32 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 33 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 34 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 35 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 36 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention;

FIG. 37 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention; and

FIG. 38 is a schematic block diagram of another embodiment of a drivesense circuit in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram of an embodiment of a communicationsystem 10 that includes a plurality of computing. devices 12-10, one ormore servers 22, one or more databases 24, one or more networks 26, aplurality of drive-sense circuits 28, a plurality of sensors 30, and aplurality of actuators 32. Computing devices 14 include a touch screen16 with sensors and drive-sensor circuits and computing devices 18include a touch & tactic screen 20 that includes sensors, actuators, anddrive-sense circuits.

A sensor 30 functions to convert a physical input into an electricaloutput and/or an optical output. The physical input of a sensor may beone of a variety of physical input conditions. For example, the physicalcondition includes one or more of, but is not limited to, acoustic waves(e.g., amplitude, phase, polarization, spectrum, and/or wave velocity);a biological and/or chemical condition (e.g., fluid concentration,level, composition, etc.); an electric condition (e.g., charge, voltage,current, conductivity, permittivity, eclectic field, which includesamplitude, phase, and/or polarization); a magnetic condition (e.g.,flux, permeability, magnetic field, which amplitude, phase, and/orpolarization); an optical condition (e.g., refractive index,reflectivity, absorption, etc.); a thermal condition (e.g., temperature,flux, specific heat, thermal conductivity, etc.); and a mechanicalcondition (e.g., position, velocity, acceleration, force, strain,stress, pressure, torque, etc.). For example, piezoelectric sensorconverts force or pressure into an eclectic signal. As another example,a microphone converts audible acoustic waves into electrical signals.

There are a variety of types of sensors to sense the various types ofphysical conditions. Sensor types include, but are not limited to,capacitor sensors, inductive sensors, accelerometers, piezoelectricsensors, light sensors, magnetic field sensors, ultrasonic sensors,temperature sensors, infrared (IR) sensors, touch sensors, proximitysensors, pressure sensors, level sensors, smoke sensors, and gassensors. In many ways, sensors function as the interface between thephysical world and the digital world by converting real world conditionsinto digital signals that are then processed by computing devices for avast number of applications including, but not limited to, medicalapplications, production automation applications, home environmentcontrol, public safety, and so on.

The various types of sensors have a variety of sensor characteristicsthat are factors in providing power to the sensors, receiving signalsfrom the sensors, and/or interpreting the signals from the sensors. Thesensor characteristics include resistance, reactance, powerrequirements, sensitivity, range, stability, repeatability, linearity,error, response time, and/or frequency response. For example, theresistance, reactance, and/or power requirements are factors indetermining drive circuit requirements. As another example, sensitivity,stability, and/or linear are factors for interpreting the measure of thephysical condition based on the received electrical and/or opticalsignal (e.g., measure of temperature, pressure, etc.).

An actuator 32 converts an electrical input into a physical output. Thephysical output of an actuator may be one of a variety of physicaloutput conditions. For example, the physical output condition includesone or more of, but is not limited to, acoustic waves (e.g., amplitude,phase, polarization, spectrum, and/or wave velocity); a magneticcondition (e.g., flux, permeability, magnetic field, which amplitude,phase, and/or polarization); a thermal condition (e.g., temperature,flux, specific heat, thermal conductivity, etc.); and a mechanicalcondition (e.g., position, velocity, acceleration, force, strain,stress, pressure, torque, etc.). As an example, a piezoelectric actuatorconverts voltage into force or pressure. As another example, a speakerconverts electrical signals into audible acoustic waves.

An actuator 32 may be one of a variety of actuators. For example, anactuator 32 is one of a comb drive, a digital micro-mirror device, anelectric motor, an electroactive polymer, a hydraulic cylinder, apiezoelectric actuator, a pneumatic actuator, a screw jack, aservomechanism, a solenoid, a stepper motor, a shape-memory allow, athermal bimorph, and a hydraulic actuator.

The various types of actuators have a variety of actuatorscharacteristics that are factors in providing power to the actuator andsending signals to the actuators for desired performance. The actuatorcharacteristics include resistance, reactance, power requirements,sensitivity, range, stability, repeatability, linearity, error, responsetime, and/or frequency response. For example, the resistance, reactance,and power requirements are factors in determining drive circuitrequirements. As another example, sensitivity, stability, and/or linearare factors for generating the signaling to send to the actuator toobtain the desired physical output condition.

The computing devices 12, 14, and 18 may each be a portable computingdevice and/or a fixed computing device. A portable computing device maybe a social networking device, a gaming device, a cell phone, a smartphone, a digital assistant, a digital music player, a digital videoplayer, a laptop computer, a handheld computer, a tablet, a video gamecontroller, and/or any other portable device that includes a computingcore. A fixed computing device may be a computer (PC), a computerserver, a cable set-top box, a satellite receiver, a television set, aprinter, a fax machine, home entertainment equipment, a video gameconsole, and/or any type of home or office computing equipment. Thecomputing devices 12, 14, and 18 will be discussed in greater detailwith reference to one or more of FIGS. 2-4.

A server 22 is a special type of computing device that is optimized forprocessing large amounts of data requests in parallel. A server 22includes similar components to that of the computing devices 12, 14,and/or 18 with more robust processing modules, more main memory, and/ormore hard drive memory (e.g., solid state, hard drives, etc.). Further,a server 22 is typically accessed remotely; as such it does notgenerally include user input devices and/or user output devices. Inaddition, a server may be a standalone separate computing device and/ormay be a cloud computing device.

A database 24 is a special type of computing device that is optimizedfor large scale data storage and retrieval. A database 24 includessimilar components to that of the computing devices 12, 14, and/or 18with more hard drive memory (e.g., solid state, hard drives, etc.) andpotentially with more processing modules and/or main memory. Further, adatabase 24 is typically accessed remotely; as such it does notgenerally include user input devices and/or user output devices. Inaddition, a database 24 may be a standalone separate computing deviceand/or may be a cloud computing device.

The network 26 includes one more local area networks (LAN) and/or one ormore wide area networks WAN), which may be a public network and/or aprivate network. A LAN may be a wireless-LAN (e.g., Wi-Fi access point,Bluetooth, ZigBee, etc.) and/or a wired network (e.g., Firewire,Ethernet, etc.). A WAN may be a wired and/or wireless WAN. For example,a LAN may be a personal home or business's wireless network and a WAN isthe Internet, cellular telephone infrastructure, and/or satellitecommunication infrastructure.

In an example of operation, computing device 12-1 communicates with aplurality of drive-sense circuits 28, which, in turn, communicate with aplurality of sensors 30. The sensors 30 and/or the drive-sense circuits28 are within the computing device 12-1 and/or external to it. Forexample, the sensors 30 may be external to the computing device 12-1 andthe drive-sense circuits are within the computing device 12-1. Asanother example, both the sensors 30 and the drive-sense circuits 28 areexternal to the computing device 12-1. When the drive-sense circuits 28are external to the computing device, they are coupled to the computingdevice 12-1 via wired and/or wireless communication links as will bediscussed in greater detail with reference to one or more of FIGS.5A-5C.

The computing device 12-1 communicates with the drive-sense circuits 28to; (a) turn them on, (b) obtain data from the sensors (individuallyand/or collectively), (c) instruct the drive sense circuit on how tocommunicate the sensed data to the computing device 12-1, (d) providesignaling attributes (e.g., DC level, AC level, frequency, power level,regulated current signal, regulated voltage signal, regulation of animpedance, frequency patterns for various sensors, different frequenciesfor different sensing applications, etc.) to use with the sensors,and/or (e) provide other commands and/or instructions.

As a specific example, the sensors 30 are distributed along a pipelineto measure flow rate and/or pressure within a section of the pipeline.The drive-sense circuits 28 have their own power source (e.g., battery,power supply, etc.) and are proximally located to their respectivesensors 30. At desired time intervals (milliseconds, seconds, minutes,hours, etc.), the drive-sense circuits 28 provide a regulated sourcesignal or a power signal to the sensors 30. An electrical characteristicof the sensor 30 affects the regulated source signal or power signal,which is reflective of the condition (e.g., the flow rate and/or thepressure) that sensor is sensing.

The drive-sense circuits 28 detect the effects on the regulated sourcesignal or power signals as a result of the electrical characteristics ofthe sensors. The drive-sense circuits 28 then generate signalsrepresentative of change to the regulated source signal or power signalbased on the detected effects on the power signals. The changes to theregulated source signals or power signals are representative of theconditions being sensed by the sensors 30.

The drive-sense circuits 28 provide the representative signals of theconditions to the computing device 12-1. A representative signal may bean analog signal or a digital signal. In either case, the computingdevice 12-1 interprets the representative signals to determine thepressure and/or flow rate at each sensor location along the pipeline.The computing device may then provide this information to the server 22,the database 24, and/or to another computing device for storing and/orfurther processing.

As another example of operation, computing device 12-2 is coupled to adrive-sense circuit 28, which is, in turn, coupled to a senor 30. Thesensor 30 and/or the drive-sense circuit 28 may be internal and/orexternal to the computing device 12-2. In this example, the sensor 30 issensing a condition that is particular to the computing device 12-2. Forexample, the sensor 30 may be a temperature sensor, an ambient lightsensor, an ambient noise sensor, etc. As described above, wheninstructed by the computing device 12-2 (which may be a default settingfor continuous sensing or at regular intervals), the drive-sense circuit28 provides the regulated source signal or power signal to the sensor 30and detects an effect to the regulated source signal or power signalbased on an electrical characteristic of the sensor. The drive-sensecircuit generates a representative signal of the affect and sends it tothe computing device 12-2.

In another example of operation, computing device 12-3 is coupled to aplurality of drive-sense circuits 28 that are coupled to a plurality ofsensors 30 and is coupled to a plurality of drive-sense circuits 28 thatare coupled to a plurality of actuators 32. The generally functionalityof the drive-sense circuits 28 coupled to the sensors 30 in accordancewith the above description.

Since an actuator 32 is essentially an inverse of a sensor in that anactuator converts an electrical signal into a physical condition, whilea sensor converts a physical condition into an electrical signal, thedrive-sense circuits 28 can be used to power actuators 32. Thus, in thisexample, the computing device 12-3 provides actuation signals to thedrive-sense circuits 28 for the actuators 32. The drive-sense circuitsmodulate the actuation signals on to power signals or regulated controlsignals, which are provided to the actuators 32. The actuators 32 arepowered from the power signals or regulated control signals and producethe desired physical condition from the modulated actuation signals.

As another example of operation, computing device 12-x is coupled to adrive-sense circuit 28 that is coupled to a sensor 30 and is coupled toa drive-sense circuit 28 that is coupled to an actuator 32. In thisexample, the sensor 30 and the actuator 32 are for use by the computingdevice 12-x. For example, the sensor 30 may be a piezoelectricmicrophone and the actuator 32 may be a piezoelectric speaker.

FIG. 2 is a schematic block diagram of an embodiment of a computingdevice 12 (e.g., any one of 12-1 through 12-x). The computing device 12includes a core control module 40, one or more processing modules 42,one or more main memories 44, cache memory 46, a video graphicsprocessing module 48, a display 50, an Input-Output (I/O) peripheralcontrol module 52, one or more input interface modules 56, one or moreoutput interface modules 58, one or more network interface modules 60,and one or more memory interface modules 62. A processing module 42 isdescribed in greater detail at the end of the detailed description ofthe invention section and, in an alternative embodiment, has a directionconnection to the main memory 44. In an alternate embodiment, the corecontrol module 40 and the I/O and/or peripheral control module 52 areone module, such as a chipset, a quick path interconnect (QPI), and/oran ultra-path interconnect (UPI).

Each of the main memories 44 includes one or more Random Access Memory(RAM) integrated circuits, or chips. For example, a main memory 44includes four DDR4 (4th generation of double data rate) RAM chips, eachrunning at a rate of 2,400 MHz. In general, the main memory 44 storesdata and operational instructions most relevant for the processingmodule 42. For example, the core control module 40 coordinates thetransfer of data and/or operational instructions from the main memory 44and the memory 64-66. The data and/or operational instructions retrievefrom memory 64-66 are the data and/or operational instructions requestedby the processing module or will most likely be needed by the processingmodule. When the processing module is done with the data and/oroperational instructions in main memory, the core control module 40coordinates sending updated data to the memory 64-66 for storage.

The memory 64-66 includes one or more hard drives, one or more solidstate memory chips, and/or one or more other large capacity storagedevices that, in comparison to cache memory and main memory devices,is/are relatively inexpensive with respect to cost per amount of datastored. The memory 64-66 is coupled to the core control module 40 viathe I/O and/or peripheral control module 52 and via one or more memoryinterface modules 62. In an embodiment, the I/O and/or peripheralcontrol module 52 includes one or more Peripheral Component Interface(PCI) buses to which peripheral components connect to the core controlmodule 40. A memory interface module 62 includes a software driver and ahardware connector for coupling a memory device to the I/O and/orperipheral control module 52. For example, a memory interface 62 is inaccordance with a Serial Advanced Technology Attachment (SATA) port.

The core control module 40 coordinates data communications between theprocessing module(s) 42 and the network(s) 26 via the I/O and/orperipheral control module 52, the network interface module(s) 60, and anetwork card 68 or 70. A network card 68 or 70 includes a wirelesscommunication unit or a wired communication unit. A wirelesscommunication unit includes a wireless local area network (WLAN)communication device, a cellular communication device, a Bluetoothdevice, and/or a ZigBee communication device. A wired communication unitincludes a Gigabit LAN connection, a Firewire connection, and/or aproprietary computer wired connection. A network interface module 60includes a software driver and a hardware connector for coupling thenetwork card to the I/O and/or peripheral control module 52. Forexample, the network interface module 60 is in accordance with one ormore versions of IEEE 802.11, cellular telephone protocols, 10/100/1000Gigabit LAN protocols, etc.

The core control module 40 coordinates data communications between theprocessing module(s) 42 and input device(s) 72 via the input interfacemodule(s) 56 and the I/O and/or peripheral control module 52. An inputdevice 72 includes a keypad, a keyboard, control switches, a touchpad, amicrophone, a camera, etc. An input interface module 56 includes asoftware driver and a hardware connector for coupling an input device tothe I/O and/or peripheral control module 52. In an embodiment, an inputinterface module 56 is in accordance with one or more Universal SerialBus (USB) protocols.

The core control module 40 coordinates data communications between theprocessing module(s) 42 and output device(s) 74 via the output interfacemodule(s) 58 and the I/O and/or peripheral control module 52. An outputdevice 74 includes a speaker, etc. An output interface module 58includes a software driver and a hardware connector for coupling anoutput device to the I/O and/or peripheral control module 52. In anembodiment, an output interface module 56 is in accordance with one ormore audio codec protocols.

The processing module 42 communicates directly with a video graphicsprocessing module 48 to display data on the display 50. The display 50includes an LED (light emitting diode) display, an LCD (liquid crystaldisplay), and/or other type of display technology. The display has aresolution, an aspect ratio, and other features that affect the qualityof the display. The video graphics processing module 48 receives datafrom the processing module 42, processes the data to produce rendereddata in accordance with the characteristics of the display, and providesthe rendered data to the display 50.

FIG. 2 further illustrates sensors 30 and actuators 32 coupled todrive-sense circuits 28, which are coupled to the input interface module56 (e.g., USB port). Alternatively, one or more of the drive-sensecircuits 28 is coupled to the computing device via a wireless networkcard (e.g., WLAN) or a wired network card (e.g., Gigabit LAN). While notshown, the computing device 12 further includes a BIOS (Basic InputOutput System) memory coupled to the core control module 40.

FIG. 3 is a schematic block diagram of another embodiment of a computingdevice 14 that includes a core control module 40, one or more processingmodules 42, one or more main memories 44, cache memory 46, a videographics processing module 48, a touch screen 16, an Input-Output (I/O)peripheral control module 52, one or more input interface modules 56,one or more output interface modules 58, one or more network interfacemodules 60, and one or more memory interface modules 62. The touchscreen 16 includes a touch screen display 80, a plurality of sensors 30,a plurality of drive-sense circuits (DSC), and a touch screen processingmodule 82.

Computing device 14 operates similarly to computing device 12 of FIG. 2with the addition of a touch screen as an input device. The touch screenincludes a plurality of sensors (e.g., electrodes, capacitor sensingcells, capacitor sensors, inductive sensor, etc.) to detect a proximaltouch of the screen. For example, when one or more fingers touches thescreen, capacitance of sensors proximal to the touch(es) are affected(e.g., impedance changes). The drive-sense circuits (DSC) coupled to theaffected sensors detect the change and provide a representation of thechange to the touch screen processing module 82, which may be a separateprocessing module or integrated into the processing module 42.

The touch screen processing module 82 processes the representativesignals from the drive-sense circuits (DSC) to determine the location ofthe touch(es). This information is inputted to the processing module 42for processing as an input. For example, a touch represents a selectionof a button on screen, a scroll function, a zoom in-out function, etc.

FIG. 4 is a schematic block diagram of another embodiment of a computingdevice 18 that includes a core control module 40, one or more processingmodules 42, one or more main memories 44, cache memory 46, a videographics processing module 48, a touch and tactile screen 20, anInput-Output (I/O) peripheral control module 52, one or more inputinterface modules 56, one or more output interface modules 58, one ormore network interface modules 60, and one or more memory interfacemodules 62. The touch and tactile screen 20 includes a touch and tactilescreen display 90, a plurality of sensors 30, a plurality of actuators32, a plurality of drive-sense circuits (DSC), a touch screen processingmodule 82, and a tactile screen processing module 92.

Computing device 18 operates similarly to computing device 14 of FIG. 3with the addition of a tactile aspect to the screen 20 as an outputdevice. The tactile portion of the screen 20 includes the plurality ofactuators (e.g., piezoelectric transducers to create vibrations,solenoids to create movement, etc.) to provide a tactile feel to thescreen 20. To do so, the processing module creates tactile data, whichis provided to the appropriate drive-sense circuits (DSC) via thetactile screen processing module 92, which may be a stand-aloneprocessing module or integrated into processing module 42. Thedrive-sense circuits (DSC) convert the tactile data into drive-actuatesignals and provide them to the appropriate actuators to create thedesired tactile feel on the screen 20.

FIG. 5A is a schematic plot diagram of a computing subsystem 25 thatincludes a sensed data processing module 65, a plurality ofcommunication modules 61A-x, a plurality of processing modules 42A-x, aplurality of drive sense circuits 28, and a plurality of sensors 1-x,which may be sensors 30 of FIG. 1. The sensed data processing module 65is one or more processing modules within one or more servers 22 and/orone more processing modules in one or more computing devices that aredifferent than the computing devices in which processing modules 42A-xreside.

A drive-sense circuit 28 (or multiple drive-sense circuits), aprocessing module (e.g., 41A), and a communication module (e.g., 61A)are within a common computing device. Each grouping of a drive-sensecircuit(s), processing module, and communication module is in a separatecomputing device. A communication module 61A-x is constructed inaccordance with one or more wired communication protocol and/or one ormore wireless communication protocols that is/are in accordance with theone or more of the Open System Interconnection (OSI) model, theTransmission Control Protocol/Internet Protocol (TCP/IP) model, andother communication protocol module.

In an example of operation, a processing module (e.g., 42A) provides acontrol signal to its corresponding drive-sense circuit 28. Theprocessing module 42 A may generate the control signal, receive it fromthe sensed data processing module 65, or receive an indication from thesensed data processing module 65 to generate the control signal. Thecontrol signal enables the drive-sense circuit 28 to provide a drivesignal to its corresponding sensor. The control signal may furtherinclude a reference signal having one or more frequency components tofacilitate creation of the drive signal and/or interpreting a sensedsignal received from the sensor.

Based on the control signal, the drive-sense circuit 28 provides thedrive signal to its corresponding sensor (e.g., 1) on a drive & senseline. While receiving the drive signal (e.g., a power signal, aregulated source signal, etc.), the sensor senses a physical condition1-x (e.g., acoustic waves, a biological condition, a chemical condition,an electric condition, a magnetic condition, an optical condition, athermal condition, and/or a mechanical condition). As a result of thephysical condition, an electrical characteristic (e.g., impedance,voltage, current, capacitance, inductance, resistance, reactance, etc.)of the sensor changes, which affects the drive signal. Note that if thesensor is an optical sensor, it converts a sensed optical condition intoan electrical characteristic.

The drive-sense circuit 28 detects the effect on the drive signal viathe drive & sense line and processes the affect to produce a signalrepresentative of power change, which may be an analog or digitalsignal. The processing module 42A receives the signal representative ofpower change, interprets it, and generates a value representing thesensed physical condition. For example, if the sensor is sensingpressure, the value representing the sensed physical condition is ameasure of pressure (e.g., x PSI (pounds per square inch)).

In accordance with a sensed data process function (e.g., algorithm,application, etc.), the sensed data processing module 65 gathers thevalues representing the sensed physical conditions from the processingmodules. Since the sensors 1-x may be the same type of sensor (e.g., apressure sensor), may each be different sensors, or a combinationthereof; the sensed physical conditions may be the same, may each bedifferent, or a combination thereof. The sensed data processing module65 processes the gathered values to produce one or more desired results.For example, if the computing subsystem 25 is monitoring pressure alonga pipeline, the processing of the gathered values indicates that thepressures are all within normal limits or that one or more of the sensedpressures is not within normal limits.

As another example, if the computing subsystem 25 is used in amanufacturing facility, the sensors are sensing a variety of physicalconditions, such as acoustic waves (e.g., for sound proofing, soundgeneration, ultrasound monitoring, etc.), a biological condition (e.g.,a bacterial contamination, etc.) a chemical condition (e.g.,composition, gas concentration, etc.), an electric condition (e.g.,current levels, voltage levels, electro-magnetic interference, etc.), amagnetic condition (e.g., induced current, magnetic field strength,magnetic field orientation, etc.), an optical condition (e.g., ambientlight, infrared, etc.), a thermal condition (e.g., temperature, etc.),and/or a mechanical condition (e.g., physical position, force, pressure,acceleration, etc.).

The computing subsystem 25 may further include one or more actuators inplace of one or more of the sensors and/or in addition to the sensors.When the computing subsystem 25 includes an actuator, the correspondingprocessing module provides an actuation control signal to thecorresponding drive-sense circuit 28. The actuation control signalenables the drive-sense circuit 28 to provide a drive signal to theactuator via a drive & actuate line (e.g., similar to the drive & senseline, but for the actuator). The drive signal includes one or morefrequency components and/or amplitude components to facilitate a desiredactuation of the actuator.

In addition, the computing subsystem 25 may include an actuator andsensor working in concert. For example, the sensor is sensing thephysical condition of the actuator. In this example, a drive-sensecircuit provides a drive signal to the actuator and another drive sensesignal provides the same drive signal, or a scaled version of it, to thesensor. This allows the sensor to provide near immediate and continuoussensing of the actuator's physical condition. This further allows forthe sensor to operate at a first frequency and the actuator to operateat a second frequency.

In an embodiment, the computing subsystem is a stand-alone system for awide variety of applications (e.g., manufacturing, pipelines, testing,monitoring, security, etc.). In another embodiment, the computingsubsystem 25 is one subsystem of a plurality of subsystems forming alarger system. For example, different subsystems are employed based ongeographic location. As a specific example, the computing subsystem 25is deployed in one section of a factory and another computing subsystemis deployed in another part of the factory. As another example,different subsystems are employed based function of the subsystems. As aspecific example, one subsystem monitors a city's traffic lightoperation, and another subsystem monitors the city's sewage treatmentplants.

Regardless of the use and/or deployment of the computing system, thephysical conditions it is sensing, and/or the physical conditions it isactuating, each sensor and each actuator (if included) is driven andsensed by a single line as opposed to separate drive and sense lines.This provides many advantages including, but not limited to, lower powerrequirements, better ability to drive high impedance sensors, lower lineto line interference, and/or concurrent sensing functions.

FIG. 5B is a schematic block diagram of another embodiment of acomputing subsystem 25 that includes a sensed data processing module 65,a communication module 61, a plurality of processing modules 42A-x, aplurality of drive sense circuits 28, and a plurality of sensors 1-x,which may be sensors 30 of FIG. 1. The sensed data processing module 65is one or more processing modules within one or more servers 22 and/orone more processing modules in one or more computing devices that aredifferent than the computing device, devices, in which processingmodules 42A-x reside.

In an embodiment, the drive-sense circuits 28, the processing modules,and the communication module are within a common computing device. Forexample, the computing device includes a central processing unit thatincludes a plurality of processing modules. The functionality andoperation of the sensed data processing module 65, the communicationmodule 61, the processing modules 42A-x, the drive sense circuits 28,and the sensors 1-x are as discussed with reference to FIG. 5A.

FIG. 5C is a schematic block diagram of another embodiment of acomputing subsystem 25 that includes a sensed data processing module 65,a communication module 61, a processing module 42, a plurality of drivesense circuits 28, and a plurality of sensors 1-x, which may be sensors30 of FIG. 1. The sensed data processing module 65 is one or moreprocessing modules within one or more servers 22 and/or one moreprocessing modules in one or more computing devices that are differentthan the computing device in which the processing module 42 resides.

In an embodiment, the drive-sense circuits 28, the processing module,and the communication module are within a common computing device. Thefunctionality and operation of the sensed data processing module 65, thecommunication module 61, the processing module 42, the drive sensecircuits 28, and the sensors 1-x are as discussed with reference to FIG.5A.

FIG. 5D is a schematic block diagram of another embodiment of acomputing subsystem 25 that includes a processing module 42, a referencesignal circuit 100, a plurality of drive sense circuits 28, and aplurality of sensors 30. The processing module 42 includes a drive-senseprocessing block 104, a drive-sense control block 102, and a referencecontrol block 106. Each block 102-106 of the processing module 42 may beimplemented via separate modules of the processing module, may be acombination of software and hardware within the processing module,and/or may be field programmable modules within the processing module42.

In an example of operation, the drive-sense control block 104 generatesone or more control signals to activate one or more of the drive-sensecircuits 28. For example, the drive-sense control block 102 generates acontrol signal that enables of the drive-sense circuits 28 for a givenperiod of time (e.g., 1 second, 1 minute, etc.). As another example, thedrive-sense control block 102 generates control signals to sequentiallyenable the drive-sense circuits 28. As yet another example, thedrive-sense control block 102 generates a series of control signals toperiodically enable the drive-sense circuits 28 (e.g., enabled onceevery second, every minute, every hour, etc.).

Continuing with the example of operation, the reference control block106 generates a reference control signal that it provides to thereference signal circuit 100. The reference signal circuit 100generates, in accordance with the control signal, one or more referencesignals for the drive-sense circuits 28. For example, the control signalis an enable signal, which, in response, the reference signal circuit100 generates a pre-programmed reference signal that it provides to thedrive-sense circuits 28. In another example, the reference signalcircuit 100 generates a unique reference signal for each of thedrive-sense circuits 28. In yet another example, the reference signalcircuit 100 generates a first unique reference signal for each of thedrive-sense circuits 28 in a first group and generates a second uniquereference signal for each of the drive-sense circuits 28 in a secondgroup.

The reference signal circuit 100 may be implemented in a variety ofways. For example, the reference signal circuit 100 includes a DC(direct current) voltage generator, an AC voltage generator, and avoltage combining circuit. The DC voltage generator generates a DCvoltage at a first level and the AC voltage generator generates an ACvoltage at a second level, which is less than or equal to the firstlevel. The voltage combining circuit combines the DC and AC voltages toproduce the reference signal. As examples, the reference signal circuit100 generates a reference signal similar to the signals shown in FIG. 7,which will be subsequently discussed.

As another example, the reference signal circuit 100 includes a DCcurrent generator, an AC current generator, and a current combiningcircuit. The DC current generator generates a DC current a first currentlevel and the AC current generator generates an AC current at a secondcurrent level, which is less than or equal to the first current level.The current combining circuit combines the DC and AC currents to producethe reference signal.

Returning to the example of operation, the reference signal circuit 100provides the reference signal, or signals, to the drive-sense circuits28. When a drive-sense circuit 28 is enabled via a control signal fromthe drive sense control block 102, it provides a drive signal to itscorresponding sensor 30. As a result of a physical condition, anelectrical characteristic of the sensor is changed, which affects thedrive signal. Based on the detected effect on the drive signal and thereference signal, the drive-sense circuit 28 generates a signalrepresentative of the effect on the drive signal.

The drive-sense circuit provides the signal representative of the effecton the drive signal to the drive-sense processing block 104. Thedrive-sense processing block 104 processes the representative signal toproduce a sensed value 97 of the physical condition (e.g., a digitalvalue that represents a specific temperature, a specific pressure level,etc.). The processing module 42 provides the sensed value 97 to anotherapplication running on the computing device, to another computingdevice, and/or to a server 22.

FIG. 5E is a schematic block diagram of another embodiment of acomputing subsystem 25 that includes a processing module 42, a pluralityof drive sense circuits 28, and a plurality of sensors 30. Thisembodiment is similar to the embodiment of FIG. 5D with thefunctionality of the drive-sense processing block 104, a drive-sensecontrol block 102, and a reference control block 106 shown in greaterdetail. For instance, the drive-sense control block 102 includesindividual enable/disable blocks 102-1 through 102-y. An enable/disableblock functions to enable or disable a corresponding drive-sense circuitin a manner as discussed above with reference to FIG. 5D.

The drive-sense processing block 104 includes variance determiningmodules 104-1 a through y and variance interpreting modules 104-2 athrough y. For example, variance determining module 104-1 a receives,from the corresponding drive-sense circuit 28, a signal representativeof a physical condition sensed by a sensor. The variance determiningmodule 104-1 a functions to determine a difference from the signalrepresenting the sensed physical condition with a signal representing aknown, or reference, physical condition. The variance interpretingmodule 104-1 b interprets the difference to determine a specific valuefor the sensed physical condition.

As a specific example, the variance determining module 104-1 a receivesa digital signal of 1001 0110 (150 in decimal) that is representative ofa sensed physical condition (e.g., temperature) sensed by a sensor fromthe corresponding drive-sense circuit 28. With 8-bits, there are 2⁸(256) possible signals representing the sensed physical condition.Assume that the units for temperature is Celsius and a digital value of0100 0000 (64 in decimal) represents the known value for 25 degreeCelsius. The variance determining module 104-b 1 determines thedifference between the digital signal representing the sensed value(e.g., 1001 0110, 150 in decimal) and the known signal value of (e.g.,0100 0000, 64 in decimal), which is 0011 0000 (86 in decimal). Thevariance determining module 104-b 1 then determines the sensed valuebased on the difference and the known value. In this example, the sensedvalue equals 25+86*(100/256)=25+33.6=58.6 degrees Celsius.

FIG. 6 is a schematic block diagram of a drive center circuit 28-acoupled to a sensor 30. The drive sense-sense circuit 28 includes apower source circuit 110 and a power signal change detection circuit112. The sensor 30 includes one or more transducers that have varyingelectrical characteristics (e.g., capacitance, inductance, impedance,current, voltage, etc.) based on varying physical conditions 114 (e.g.,pressure, temperature, biological, chemical, etc.), or vice versa (e.g.,an actuator).

The power source circuit 110 is operably coupled to the sensor 30 and,when enabled (e.g., from a control signal from the processing module 42,power is applied, a switch is closed, a reference signal is received,etc.) provides a power signal 116 to the sensor 30. The power sourcecircuit 110 may be a voltage supply circuit (e.g., a battery, a linearregulator, an unregulated DC-to-DC converter, etc.) to produce avoltage-based power signal, a current supply circuit (e.g., a currentsource circuit, a current mirror circuit, etc.) to produce acurrent-based power signal, or a circuit that provide a desired powerlevel to the sensor and substantially matches impedance of the sensor.The power source circuit 110 generates the power signal 116 to include aDC (direct current) component and/or an oscillating component.

When receiving the power signal 116 and when exposed to a condition 114,an electrical characteristic of the sensor affects 118 the power signal.When the power signal change detection circuit 112 is enabled, itdetects the affect 118 on the power signal as a result of the electricalcharacteristic of the sensor. For example, the power signal is a 1.5voltage signal and, under a first condition, the sensor draws 1 milliampof current, which corresponds to an impedance of 1.5 K Ohms. Under asecond conditions, the power signal remains at 1.5 volts and the currentincreases to 1.5 milliamps. As such, from condition 1 to condition 2,the impedance of the sensor changed from 1.5 K Ohms to 1 K Ohms. Thepower signal change detection circuit 112 determines this change andgenerates a representative signal 120 of the change to the power signal.

As another example, the power signal is a 1.5 voltage signal and, undera first condition, the sensor draws 1 milliamp of current, whichcorresponds to an impedance of 1.5 K Ohms. Under a second conditions,the power signal drops to 1.3 volts and the current increases to 1.3milliamps. As such, from condition 1 to condition 2, the impedance ofthe sensor changed from 1.5 K Ohms to 1 K Ohms. The power signal changedetection circuit 112 determines this change and generates arepresentative signal 120 of the change to the power signal.

The power signal 116 includes a DC component 122 and/or an oscillatingcomponent 124 as shown in FIG. 7. The oscillating component 124 includesa sinusoidal signal, a square wave signal, a triangular wave signal, amultiple level signal (e.g., has varying magnitude over time withrespect to the DC component), and/or a polygonal signal (e.g., has asymmetrical or asymmetrical polygonal shape with respect to the DCcomponent). Note that the power signal is shown without affect from thesensor as the result of a condition or changing condition.

In an embodiment, power generating circuit 110 varies frequency of theoscillating component 124 of the power signal 116 so that it can betuned to the impedance of the sensor and/or to be off-set in frequencyfrom other power signals in a system. For example, a capacitancesensor's impedance decreases with frequency. As such, if the frequencyof the oscillating component is too high with respect to thecapacitance, the capacitor looks like a short and variances incapacitances will be missed. Similarly, if the frequency of theoscillating component is too low with respect to the capacitance, thecapacitor looks like an open and variances in capacitances will bemissed.

In an embodiment, the power generating circuit 110 varies magnitude ofthe DC component 122 and/or the oscillating component 124 to improveresolution of sensing and/or to adjust power consumption of sensing. Inaddition, the power generating circuit 110 generates the drive signal110 such that the magnitude of the oscillating component 124 is lessthan magnitude of the DC component 122.

FIG. 6A is a schematic block diagram of a drive center circuit 28-a 1coupled to a sensor 30. The drive sense-sense circuit 28-a 1 includes asignal source circuit 111, a signal change detection circuit 113, and apower source 115. The power source 115 (e.g., a battery, a power supply,a current source, etc.) generates a voltage and/or current that iscombined with a signal 117, which is produced by the signal sourcecircuit 111. The combined signal is supplied to the sensor 30.

The signal source circuit 111 may be a voltage supply circuit (e.g., abattery, a linear regulator, an unregulated DC-to-DC converter, etc.) toproduce a voltage-based signal 117, a current supply circuit (e.g., acurrent source circuit, a current mirror circuit, etc.) to produce acurrent-based signal 117, or a circuit that provide a desired powerlevel to the sensor and substantially matches impedance of the sensor.The signal source circuit 111 generates the signal 117 to include a DC(direct current) component and/or an oscillating component.

When receiving the combined signal (e.g., signal 117 and power from thepower source) and when exposed to a condition 114, an electricalcharacteristic of the sensor affects 119 the signal. When the signalchange detection circuit 113 is enabled, it detects the affect 119 onthe signal as a result of the electrical characteristic of the sensor.

FIG. 8 is an example of a sensor graph that plots an electricalcharacteristic versus a condition. The sensor has a substantially linearregion in which an incremental change in a condition produces acorresponding incremental change in the electrical characteristic. Thegraph shows two types of electrical characteristics: one that increasesas the condition increases and the other that decreases and thecondition increases. As an example of the first type, impedance of atemperature sensor increases and the temperature increases. As anexample of a second type, a capacitance touch sensor decreases incapacitance as a touch is sensed.

FIG. 9 is a schematic block diagram of another example of a power signalgraph in which the electrical characteristic or change in electricalcharacteristic of the sensor is affecting the power signal. In thisexample, the effect of the electrical characteristic or change inelectrical characteristic of the sensor reduced the DC component but hadlittle to no effect on the oscillating component. For example, theelectrical characteristic is resistance. In this example, the resistanceor change in resistance of the sensor decreased the power signal,inferring an increase in resistance for a relatively constant current.

FIG. 10 is a schematic block diagram of another example of a powersignal graph in which the electrical characteristic or change inelectrical characteristic of the sensor is affecting the power signal.In this example, the effect of the electrical characteristic or changein electrical characteristic of the sensor reduced magnitude of theoscillating component but had little to no effect on the DC component.For example, the electrical characteristic is impedance of a capacitorand/or an inductor. In this example, the impedance or change inimpedance of the sensor decreased the magnitude of the oscillatingsignal component, inferring an increase in impedance for a relativelyconstant current.

FIG. 11 is a schematic block diagram of another example of a powersignal graph in which the electrical characteristic or change inelectrical characteristic of the sensor is affecting the power signal.In this example, the effect of the electrical characteristic or changein electrical characteristic of the sensor shifted frequency of theoscillating component but had little to no effect on the DC component.For example, the electrical characteristic is reactance of a capacitorand/or an inductor. In this example, the reactance or change inreactance of the sensor shifted frequency of the oscillating signalcomponent, inferring an increase in reactance (e.g., sensor isfunctioning as an integrator or phase shift circuit).

FIG. 11A is a schematic block diagram of another example of a powersignal graph in which the electrical characteristic or change inelectrical characteristic of the sensor is affecting the power signal.In this example, the effect of the electrical characteristic or changein electrical characteristic of the sensor changes the frequency of theoscillating component but had little to no effect on the DC component.For example, the sensor includes two transducers that oscillate atdifferent frequencies. The first transducer receives the power signal ata frequency of f1 and converts it into a first physical condition. Thesecond transducer is stimulated by the first physical condition tocreate an electrical signal at a different frequency f2. In thisexample, the first and second transducers of the sensor change thefrequency of the oscillating signal component, which allows for moregranular sensing and/or a broader range of sensing.

FIG. 12 is a schematic block diagram of an embodiment of a power signalchange detection circuit 112 receiving the affected power signal 118 andthe power signal 116 as generated to produce, therefrom, the signalrepresentative 120 of the power signal change. The affect 118 on thepower signal is the result of an electrical characteristic and/or changein the electrical characteristic of a sensor; a few examples of theaffects are shown in FIGS. 8-11A.

In an embodiment, the power signal change detection circuit 112 detect achange in the DC component 122 and/or the oscillating component 124 ofthe power signal 116. The power signal change detection circuit 112 thengenerates the signal representative 120 of the change to the powersignal based on the change to the power signal. For example, the changeto the power signal results from the impedance of the sensor and/or achange in impedance of the sensor. The representative signal 120 isreflective of the change in the power signal and/or in the change in thesensor's impedance.

In an embodiment, the power signal change detection circuit 112 isoperable to detect a change to the oscillating component at a frequency,which may be a phase shift, frequency change, and/or change in magnitudeof the oscillating component. The power signal change detection circuit112 is also operable to generate the signal representative of the changeto the power signal based on the change to the oscillating component atthe frequency. The power signal change detection circuit 112 is furtheroperable to provide feedback to the power source circuit 110 regardingthe oscillating component. The feedback allows the power source circuit110 to regulate the oscillating component at the desired frequency,phase, and/or magnitude.

FIG. 13 is a schematic block diagram of another embodiment of a drivesense circuit 28-a 2 that includes a current source 110-1 and a powersignal change detection circuit 112-a 1. The power signal changedetection circuit 112-a 1 includes a power source reference circuit 130and a comparator 132. The current source 110-1 may be an independentcurrent source, a dependent current source, a current mirror circuit,etc.

In an example of operation, the power source reference circuit 130provides a current reference 134 with DC and oscillating components tothe current source 110-1. The current source generates a current as thepower signal 116 based on the current reference 134. An electricalcharacteristic of the sensor 30 has an effect on the current powersignal 116. For example, if the impedance of the sensor decreases andthe current power signal 116 remains substantially unchanged, thevoltage across the sensor is decreased.

The comparator 132 compares the current reference 134 with the affectedpower signal 118 to produce the signal 120 that is representative of thechange to the power signal. For example, the current reference signal134 corresponds to a given current (I) times a given impedance (Z). Thecurrent reference generates the power signal to produce the givencurrent (I). If the impedance of the sensor 30 substantially matches thegiven impedance (Z), then the comparator's output is reflective of theimpedances substantially matching. If the impedance of the sensor 30 isgreater than the given impedance (Z), then the comparator's output isindicative of how much greater the impedance of the sensor 30 is thanthat of the given impedance (Z). If the impedance of the sensor 30 isless than the given impedance (Z), then the comparator's output isindicative of how much less the impedance of the sensor 30 is than thatof the given impedance (Z).

FIG. 14 is a schematic block diagram of another embodiment of a drivesense circuit 28-a 3 that includes a voltage source 110-2 and a powersignal change detection circuit 112-a 2. The power signal changedetection circuit 112-a 2 includes a power source reference circuit130-2 and a comparator 132-2. The voltage source 110-2 may be a battery,a linear regulator, a DC-DC converter, etc.

In an example of operation, the power source reference circuit 130-2provides a voltage reference 136 with DC and oscillating components tothe voltage source 110-2. The voltage source generates a voltage as thepower signal 116 based on the voltage reference 136. An electricalcharacteristic of the sensor 30 has an effect on the voltage powersignal 116. For example, if the impedance of the sensor decreases andthe voltage power signal 116 remains substantially unchanged, thecurrent through the sensor is increased.

The comparator 132 compares the voltage reference 136 with the affectedpower signal 118 to produce the signal 120 that is representative of thechange to the power signal. For example, the voltage reference signal134 corresponds to a given voltage (V) divided by a given impedance (Z).The voltage reference generates the power signal to produce the givenvoltage (V). If the impedance of the sensor 30 substantially matches thegiven impedance (Z), then the comparator's output is reflective of theimpedances substantially matching. If the impedance of the sensor 30 isgreater than the given impedance (Z), then the comparator's output isindicative of how much greater the impedance of the sensor 30 is thanthat of the given impedance (Z). If the impedance of the sensor 30 isless than the given impedance (Z), then the comparator's output isindicative of how much less the impedance of the sensor 30 is than thatof the given impedance (Z).

FIG. 15 is a schematic block diagram of another embodiment of a drivesense circuit 28-a 4 that includes the power source circuit 110, thepower signal change detection circuit 112, an analog to digitalconverter 140, and a driver 142. The power source circuit 110 and thepower signal change detection circuit 112 function as previouslydiscussed with reference to FIG. 13 to produce a signal 120 that isrepresentative of a power signal change.

In this embodiment, the power source circuit 110 provides its output tothe driver 142, which functions to increase the power (e.g., increasevoltage and/or current) of the power signal produced by the power sourcecircuit 110. The driver 142 provides the power signal 116 to the sensor30. With a driver, which may be a power amplifier, a low impedancesensor 30 may be used of specific types for sensing applications.

The analog to digital converter 140 converts the signal 120 thatrepresents the power signal change into a digital signal 144. Thedigital signal 144 is provided to the processing module 42 via aconnection between the drive-sense circuit and the processing module.The processing module converts the digital signal into a relative valueof the condition to which the sensor is exposed. The connection betweenthe drive-sense circuit 28-a 4 and the processing module 42 depends onwhether the drive-sense circuit is internal or external to the computingdevice of the processing module. If internal, then the drive-sensecircuit is connected to the processing module via a PCI bus or the like.If the drive-sense circuit is external to the processing module, thenthe connection is a USB connection, a Bluetooth connection, a WLANconnection, an internet connection, and/or a WAN connection.

FIG. 16 is a schematic block diagram of another embodiment of a drivesense circuit 28-b includes a change detection circuit 150, a regulationcircuit 152, and a power source circuit 154. The drive-sense circuit28-b is coupled to the sensor 30, which includes a transducer that hasvarying electrical characteristics (e.g., capacitance, inductance,impedance, current, voltage, etc.) based on varying physical conditions114 (e.g., pressure, temperature, biological, chemical, etc.).

The power source circuit 154 is operably coupled to the sensor 30 and,when enabled (e.g., from a control signal from the processing module 42,power is applied, a switch is closed, a reference signal is received,etc.) provides a power signal 158 to the sensor 30. The power sourcecircuit 154 may be a voltage supply circuit (e.g., a battery, a linearregulator, an unregulated DC-to-DC converter, etc.) to produce avoltage-based power signal or a current supply circuit (e.g., a currentsource circuit, a current mirror circuit, etc.) to produce acurrent-based power signal. The power source circuit 154 generates thepower signal 158 to include a DC (direct current) component and anoscillating component.

When receiving the power signal 158 and when exposed to a condition 114,an electrical characteristic of the sensor affects 160 the power signal.When the change detection circuit 150 is enabled, it detects the affect160 on the power signal as a result of the electrical characteristic ofthe sensor 30. The change detection circuit 150 is further operable togenerate a signal 120 that is representative of change to the powersignal based on the detected effect on the power signal.

The regulation circuit 152, when its enabled, generates regulationsignal 156 to regulate the DC component to a desired DC level and/orregulate the oscillating component to a desired oscillating level (e.g.,magnitude, phase, and/or frequency) based on the signal 120 that isrepresentative of the change to the power signal. The power sourcecircuit 154 utilizes the regulation signal 156 to keep the power signalat a desired setting 158 regardless of the electrical characteristic ofthe sensor. In this manner, the amount of regulation is indicative ofthe affect the electrical characteristic had on the power signal.

In an example, the power source circuit 158 is a DC-DC converteroperable to provide a regulated power signal having DC and ACcomponents. The change detection circuit 150 is a comparator and theregulation circuit 152 is a pulse width modulator to produce theregulation signal 156. The comparator compares the power signal 158,which is affected by the sensor, with a reference signal that includesDC and AC components. When the electrical characteristics is at a firstlevel (e.g., a first impedance), the power signal is regulated toprovide a voltage and current such that the power signal substantiallyresembles the reference signal.

When the electrical characteristics changes to a second level (e.g., asecond impedance), the change detection circuit 150 detects a change inthe DC and/or AC component of the power signal 158 and generates therepresentative signal 120, which indicates the changes. The regulationcircuit 152 detects the change in the representative signal 120 andcreates the regulation signal to substantially remove the effect on thepower signal. The regulation of the power signal 158 may be done byregulating the magnitude of the DC and/or AC components, by adjustingthe frequency of AC component, and/or by adjusting the phase of the ACcomponent.

FIG. 17 is a schematic block diagram of another embodiment of a drivesense circuit 28-b 1 that includes a current source 154-1 and a changedetection circuit 150-1. The change detection circuit 150-1 includes apower source reference circuit 162 and a comparator 164. The currentsource 154-1 may be an independent current source, a dependent currentsource, a current mirror circuit, etc.

In an example of operation, the power source reference circuit 162provides a current reference with DC and/or oscillating components tothe comparator 164. The comparator 164 compares the reference currentwith the current power signal 158 generated by the current source 154-1and produces, based on the comparison, the representative signal 120.

The regulation circuit 152, which includes a feedback circuit 166 (e.g.,a dependent current source biasing circuit, a wire, etc.), generates aregulation signal 156-1 based on the representative signal 120 andprovides the regulation signal to the current source 154-1. The currentsource generates a regulated current as the power signal 116 based onthe regulation signal 156-1.

As an example, the current reference signal corresponds to a givencurrent (I) times a given impedance (Z). The current source 154-1generates the power signal to produce the given current (I). If theimpedance of the sensor 30 substantially matches the given impedance(Z), then the comparator's output is reflective of the impedancessubstantially matching. If the impedance of the sensor 30 is greaterthan the given impedance (Z), then the comparator's output is indicativeof how much greater the impedance of the sensor 30 is than that of thegiven impedance (Z). If the impedance of the sensor 30 is less than thegiven impedance (Z), then the comparator's output is indicative of howmuch less the impedance of the sensor 30 is than that of the givenimpedance (Z). The regulation circuit functions to account for thevariations in the impedance of the sensor and to ensure that the currentsource produces a regulated current source (e.g., it remainssubstantially at the given current (I)).

FIG. 18 is a schematic block diagram of another embodiment of a drivesense circuit 28-b 2 that includes a voltage source 154-2 and a changedetection circuit 150-2. The change detection circuit 150-2 includes apower source reference circuit 162-2 and a comparator 164-2. The voltagesource 154-2 may be a linear regulator, a DC-DC converter, etc.

In an example of operation, the power source reference circuit 162-2provides a voltage reference with DC and oscillating components to thecomparator 164-2. The comparator 164-2 compares the reference voltagewith the voltage power signal 158 generated by the voltage source 154-2and produces, based on the comparison, the representative signal 120.

The regulation circuit 152, which includes a feedback circuit 166-2(e.g., a power supply regulation circuit, a bias circuit, a wire, etc.),generates a regulation signal 156-2 based on the representative signal120 and provides the regulation signal to the voltage source 154-2. Thevoltage source generates a regulated voltage as the power signal 116based on the regulation signal 156-1.

As an example, the voltage reference signal corresponds to a givenvoltage (V) divided by a given impedance (Z). The voltage source 154-2generates the power signal to produce the given voltage (V). If theimpedance of the sensor 30 substantially matches the given impedance(Z), then the comparator's output is reflective of the impedancessubstantially matching. If the impedance of the sensor 30 is greaterthan the given impedance (Z), then the comparator's output is indicativeof how much greater the impedance of the sensor 30 is than that of thegiven impedance (Z). If the impedance of the sensor 30 is less than thegiven impedance (Z), then the comparator's output is indicative of howmuch less the impedance of the sensor 30 is than that of the givenimpedance (Z). The regulation circuit functions to account for thevariations in the impedance of the sensor and to ensure that the voltagesource produces a regulated voltage source (e.g., it remainssubstantially at the given voltage (V)).

FIG. 19 is a schematic block diagram of another embodiment of a drivesense circuit 28-b 3 that includes the power source circuit 154, thechange detection circuit 150, the regulation circuit 152, an analog todigital converter 140, and a driver 142. The power source circuit 154,the regulation circuit 152, and the change detection circuit 150function as previously discussed with reference to FIG. 16 to producethe regulation signal 156 and the signal 120 that is representative of apower signal change.

In this embodiment, the power source circuit 154 provides its output tothe driver 142, which functions to increase the power (e.g., increasevoltage and/or current) of the power signal. The driver 142 provides thepower signal 116 to the sensor 30. With a driver, which may be a poweramplifier, a low impedance sensor 30 may be used for specific types ofsensing applications.

The analog to digital converter 140 converts the signal 120 thatrepresents the power signal change into a digital signal 144. Thedigital signal 144 is provided to the processing module 42 via aconnection between the drive-sense circuit and the processing module.

FIG. 20 is a schematic block diagram of another embodiment of adrive-sense circuit 28 that includes a power supply circuit 155 and anoperational amplifier (op amp) or comparator 172. The power supplycircuit 155 may be implemented in a variety of ways. For example, thepower supply circuit 155 is a linear regulator that steps down a DCinput voltage (DC in) to produce the power signal 174 based on aregulation signal 156-3. As another example, the power supply circuit155 is a DC-DC converter that steps up or steps down the DC inputvoltage based on the regulation signal to produce the power signal 174.

The op amp 172 compares the power signal 174 with the power signalreference to produce the regulation signal 156-3, which is also thesignal 120 representing a power signal change. In a specific embodiment,the power supply circuit 155 includes a P-channel FET (field effecttransistor) and a bias circuit. The source of the P-channel FET iscoupled to the DC input, the gate to the bias circuit, and the drain iscoupled to provide the power signal 174. The bias circuit receives theregulation signal 156-3 and adjusts a gate-source voltage such that thevoltage of the power signal 174 substantially matches the voltage of thepower signal reference 170. For example, if the power signal referencehas a DC component and/or an oscillating component as shown in FIG. 7,then the power signal 174 will have a substantially similar DC componentand/or oscillating component.

When the power signal 174 is provided to a sensor and the sensor isexposed to a condition, an electrical characteristic of the sensor willaffect the power signal. The control loop that regulates the voltage ofthe power signal 174 to substantially match the voltage of the powerreference signal 170 will adjust the regulation signal to compensate forthe affects the sensor has on the power signal 174. The compensationcorresponds to the affect the electrical characteristic of the sensorhas on the power signal and is representative of the condition beingsensed by the sensor. Thus, the regulation signal 156-3 provides boththe regulation of the power supply circuit 155 and the signal 120 thatrepresents the effect on the power signal.

FIG. 21 is a schematic block diagram of another embodiment of adrive-sense circuit 28 that includes a dependent current source 182 anda transimpedance amplifier 180, which functions as a current comparatorin this embodiment. The dependent current source 182 may be implementedin a variety of ways. For example, the dependent current source 182 is acurrent mirror circuit sourced via a DC input voltage (DC in) to producethe power signal 184 based on a regulation signal 156-3. As anotherexample, the dependent current source 182 is voltage controlled currentsource. As yet another example, the dependent current source 182 iscurrent controlled current source.

The transimpedance amplifier 180 compares current of the power signal174 with current of the power signal reference 186 to produce theregulation signal 156-4, which is also the signal 120 representing apower signal change. In a specific embodiment, the power supply circuit155 includes a P-channel FET (field effect transistor) and a biascircuit. The source of the P-channel FET is coupled to the DC input, thegate to the bias circuit, and the drain is coupled to provide the powersignal 184. The bias circuit receives the regulation signal 156-4 andadjusts a gate-source voltage such that the current of the power signal184 substantially matches the current of the power signal reference 186.

When the current of the power signal 184 is provided to a sensor and thesensor is exposed to a condition, an electrical characteristic of thesensor will affect the power signal. The control loop that regulates thecurrent of the power signal 184 to substantially match the current ofthe power reference signal 186 will adjust the regulation signal tocompensate for the affects the sensor has on the power signal 184. Thecompensation corresponds to the affect the electrical characteristic ofthe sensor has on the power signal and is representative of thecondition being sensed by the sensor. Thus, the regulation signal 156-4provides both the regulation of the dependent current source 182 and thesignal 120 that represents the effect on the power signal.

FIG. 22 is a schematic block diagram of another embodiment of a drivesense circuit 28-c, which is coupled to a sensor 30. The drive sensecircuit 28-c includes analog circuitry 190 and digital circuitry 192.When the analog circuitry 190 is enabled, it is operable to generate aregulated source signal 196 based on an analog regulation signal 204.The analog circuitry is enabled in a variety of ways. For example, theanalog circuitry 190 is enable when power is applied to the drive sensecircuit 28-c. As another example, the analog circuitry 190 is enabledwhen the drive sense circuit receives a control signal from theprocessing module.

The analog circuitry 190 provides the regulated source signal 196 to thesensor 30. The regulated source signal 196 may be a regulated currentsignal, a regulated voltage signal, or a regulated impedance signal.When the sensor 30 is exposed to a condition 114, an electricalcharacteristic of the sensor affects 198 the regulated source signal.

In addition to generating the regulated source signal 196, the analogcircuitry 190 also generates a reference source signal 194 at a desiredsource level. For example, the reference source signal 194 is generatedto include a DC component having a magnitude and/or an oscillatingcomponent having a waveform (e.g., sinusoidal, square, triangular,polygonal, multiple step, etc.), a frequency, a phase, and a magnitude.The analog circuitry 190 is further operable to compare the regulatedsource signal 196 to the reference source signal 194 to produce acomparison signal 200. The comparison signal 200 corresponds to theaffect the electrical characteristic of the sensor has on the regulatedsource signal and is representative of the condition 114 being sensed bythe sensor 30.

When the digital circuitry is enabled, it is operable to convert thecomparison signal 200 into a digital signal 202. The digital signal is adigital representation of the comparison signal and, as such,corresponds to the affect the electrical characteristic of the sensorhas on the regulated source signal and is representative of thecondition 114 being sensed by the sensor 30. The digital circuitry 192is further operable to convert the digital signal 202 into the analogregulation signal 204.

FIG. 23 is a schematic block diagram of another embodiment of a drivesense circuit 28-c 1 that includes the analog circuitry 190 and thedigital circuitry 192. The analog circuitry 190 includes a dependentcurrent source 216, a comparator 210, an analog portion of an analog todigital converter 212, and an analog portion of a digital to analogconverter 214. The digital circuitry 192 includes a digital portion ofthe analog to digital converter 212, and a digital portion of thedigital to analog converter 214. The analog to digital converter (ADC)212 may be a flash ADC, a successive approximation ADC, a ramp-compareADC, a Wilkinson ADC, an integrating ADC, a delta encoded ADC, and/or asigma-delta ADC. The digital to analog converter (DAC) 214 may be asigma-delta DAC, a pulse width modulator DAC, a binary weighted DAC, asuccessive approximation DAC, and/or a thermometer-coded DAC.

The dependent current source 216 generates the regulated source signal196-1 as a regulated current signal based on the analog regulationsignal 220. The comparator 210 compares the regulated source signal196-1 with a reference source signal 194-1, which is a current referencesignal having a DC component and/or an oscillating component. Thecomparison signal 218 corresponds to the effect on the regulated sourcesignal 196-1 and is representative of the condition 114 being sensed bythe sensor 30. The comparator 210 provides the comparison signal 218 tothe analog to digital converter 212, which generates the digital signal202. The digital to analog converter 214 converts the digital signalinto the analog regulation signals 220.

FIG. 24 is a schematic block diagram of another embodiment of a drivesense circuit 28-c 2 that includes the analog circuitry 190 and thedigital circuitry 192. The analog circuitry 190 includes a voltagesource circuit 216, a change detection circuit 224, an analog portion ofan analog to digital converter 212-2, and an analog portion of a digitalto analog converter 214-2. The digital circuitry 192 includes a digitalportion of the analog to digital converter 212-2, and a digital portionof the digital to analog converter 214-2. The analog to digitalconverter 212-2 and the digital to analog converter 214-2 are one ormore of the types discussed with reference to FIG. 23.

The voltage source circuit 226 (e.g., a power supply, a linearregulator, a biased transistor, etc.) generates the regulated sourcesignal 196-2 as a regulated voltage signal based on the analogregulation signal 220-2. The change detection circuit 224 (e.g., an opamp, a comparator, etc.) compares the regulated source signal 196-2 witha reference source signal 194-2, which is a voltage reference signalhaving a DC component and/or an oscillating component. The comparisonsignal 218-2 corresponds to the effect on the regulated source signal196-2 and is representative of the condition 114 being sensed by thesensor 30. The change detection circuit 224 provides the comparisonsignal 218-2 to the analog to digital converter 212-2, which generatesthe digital signal 202. The digital to analog converter 214-2 convertsthe digital signal into the analog regulation signals 220-2.

FIG. 25 is a schematic block diagram of another embodiment of a drivesense circuit 28-d coupled to a variable impedance sensor 30-1. Thedrive sense circuit 28-d includes a voltage (V) reference circuit 230, acurrent (I) loop correction circuit 232, and a regulated current (I)source circuit 234. In general, the drive sense circuit 28-d regulatesthe current applied to the sensor and keeps the voltage constant tosense an impedance (Z) of the sensor 30-1 in relation to a sensorvoltage 246 and a voltage reference 236.

When the drive sense circuit 28-d is enabled, the regulated currentsource circuit 234 is operable to generate a regulated current signal238 based on an analog regulation signal 242. The regulated currentsource circuit 234 generates the regulated current signal 238 such thatthe sensor voltage 246 substantially matches a voltage reference 236produced by the V reference circuit 230.

The V reference circuit 230 (which may be a bandgap reference, aregulator, a divider network, an AC generator, and/or combining circuit)generates the voltage reference 236 to include a DC component and/or atleast one oscillating component. For example, the V reference circuitgenerates a DC component to have a magnitude between 1 and 3 volts,generates a first sinusoidal oscillating component at frequency 1, andgenerates a second sinusoidal oscillating component at frequency 2. As aspecific example, the first sinusoidal oscillating component atfrequency 1 is used to sense self-touch on a touch screen display andthe second sinusoidal oscillating component at frequency 2 is used tosense mutual touch on the touch screen display.

The regulated current source circuit 234 provides the regulated currentsignal 238 to the sensor 30-1. When the sensor 30-1 is exposed to acondition 114-1, its impedance affects 240 the regulated current signal238 based on V=I*Z. As such, the sensor voltage 246 is created as aresult of the current (I) provided by the regulated current sourcecircuit 234 and the impedance of the sensor 30-1. As the impedance ofthe sensor 30-1 changes due to changing conditions 114-1, the currentprovided by the regulated current source circuit 234 changes so that thesensor voltage 246 remains substantially equal to the voltage reference236, including the DC component and/or the oscillating component(s).

The current (I) loop correction circuit 232 is operable to generate acomparison signal 244 based on a comparison of the sensor voltage 246with the voltage reference 236. The effect of the impedance of thesensor on the regulated current signal 238 is detected by the I loopcorrection circuit 232 and captured by the comparison signal 244. The Iloop correction circuit 232 is further operable to convert thecomparison signal 244 into a digital signal 202, which is a digitalrepresentation of the affect the impedance of the sensor has on theregulated current signal and corresponds to the sensed condition 114-1.The I loop correction circuit is further operable to convert the digitalsignal 202 into the analog regulation signal 242, thereby creating afeedback loop to keep the sensor voltage 246 substantially equal to thevoltage reference 236.

FIG. 26 is a schematic block diagram of another embodiment of a drivesense circuit 28-d 1 coupled to a variable impedance sensor 30-1. Thedrive sense circuit 28-d 1 includes the voltage (V) reference circuit230, a current (I) loop correction circuit 232-1, and a regulatedcurrent (I) source circuit 234-1. The regulated current (I) sourcecircuit 234-1 includes a dependent current source and the I loopcorrection circuit 232-1 includes a voltage comparator or op amp 250, ananalog to digital converter 212-3 and a digital to analog converter214-3. The analog to digital converter 212-3 and the digital to analogconverter 214-3 are one or more of the types discussed with reference toFIG. 23.

When the drive sense circuit 28-d 1 is enabled, the regulated currentsource circuit 234-1 is operable to generate a regulated current signal238-1 based on an analog regulation signal 242-1. The regulated currentsource circuit 234-1 generates the regulated current signal 238-1 suchthat the sensor voltage 246-1 substantially matches the voltagereference 236 produced by the V reference circuit 230.

The regulated current source circuit 234-1 provides the regulatedcurrent signal 238-1 to the sensor 30-1. When the sensor 30-1 is exposedto a condition 114-1, its impedance affects 240-1 the regulated currentsignal 238-1 based on V=I*Z. As such, the sensor voltage 246-1 iscreated as a result of the current (I) provided by the regulated currentsource circuit 234-1 and the impedance of the sensor 30-1. As theimpedance of the sensor 30-1 changes due to changing conditions 114-1,the current provided by the regulated current source circuit 234-1changes so that the sensor voltage 246-1 remains substantially equal tothe voltage reference 236-1, including the DC component and/or theoscillating component(s).

The comparator 250 compares the sensor voltage 246-1 with the voltagereference 236 to produce a comparison signal 244-1. The effect of theimpedance of the sensor on the regulated current signal 238-1 iscaptured by the comparison signal 244-1. The analog to digital converter212-3 converts the comparison signal 244-1 into a digital signal 202,which is a digital representation of the affect the impedance of thesensor has on the regulated current signal and corresponds to the sensedcondition 114-1. The digital to analog converter 214-3 converts thedigital signal 202 into the analog regulation signal 242-1, therebycreating a feedback loop to keep the sensor voltage 246-1 substantiallyequal to the voltage reference 236.

FIG. 26A is a schematic block diagram of another embodiment of a drivesense circuit coupled to a variable impedance sensor 30-1. The drivesense circuit 28-d 2 includes the voltage (V) reference circuit 230, acurrent (I) loop correction circuit 232-2, and a regulated current (I)source circuit 234-2. The regulated current (I) source circuit 234-2includes a dependent current source and the I loop correction circuit232-2 includes a voltage comparator or op amp 250 and an analog todigital converter 212-3 a. The analog to digital converter 212-3 a isone or more of the types discussed with reference to FIG. 23.

When the drive sense circuit 28-d 2 is enabled, the regulated currentsource circuit 234-2 is operable to generate a regulated current signal238-2 based on a comparison signal 244-2. The regulated current sourcecircuit 234-2 generates the regulated current signal 238-2 such that thesensor voltage 246-2 substantially matches the voltage reference 236produced by the V reference circuit 230. In an example, the comparisonsignal operates similar to the analog regulation signal 242-1 of FIG. 26to create a feedback loop to keep the sensor voltage 246-1 substantiallyequal to the voltage reference 236.

The regulated current source circuit 234-2 provides the regulatedcurrent signal 238-2 to the sensor 30-1. When the sensor 30-1 is exposedto a condition 114-2, its impedance affects 240-2 the regulated currentsignal 238-2 based on V=I*Z. As such, the sensor voltage 246-2 iscreated as a result of the current (I) provided by the regulated currentsource circuit 234-2 and the impedance of the variable impedance sensor30-2. As the impedance of the variable impedance sensor 30-2 changes dueto changing conditions 114-2, the current provided by the regulatedcurrent source circuit 234-2 changes so that the sensor voltage 246-2remains substantially equal to the voltage reference 236, including theDC component and/or the oscillating component(s).

The comparator 250 compares the sensor voltage 246-2 with the voltagereference 236 to produce a comparison signal 244-2. The effect of theimpedance of the sensor on the regulated current signal 238-2 iscaptured by the comparison signal 244-2. The analog to digital converter212-3 a converts the comparison signal 244-2 into a digital signal 202,which is a digital representation of the affect the impedance of thesensor has on the regulated current signal and corresponds to the sensedcondition 114-2.

FIG. 27 is a schematic block diagram of another embodiment of a drivesense circuit 28-e coupled to a variable impedance sensor 30-1. Thedrive sense circuit 28-e includes a current (I) reference circuit 260, avoltage (V) loop correction circuit 262, and a regulated voltage (V)source circuit 264. In general, the drive sense circuit 28-e regulatesthe voltage applied to the sensor and keeps the current constant tosense an impedance (Z) of the sensor 30-1 in relation to a sensorcurrent 272 and a current reference 270.

When the drive sense circuit 28-e is enabled, the regulated voltagesource circuit 264 is operable to generate a regulated voltage signal266 based on an analog regulation signal 274. The regulated voltagesource circuit 264 generates the regulated voltage signal 266 such thatthe sensor current 272 substantially matches the current reference 270produced by the I reference circuit 260.

The I reference circuit 260 (which may be a biased dependent currentsource, an independent current source, a current mirror, an AC currentgenerator, and/or combining circuit) generates the current reference 270to include a DC component and/or at least one oscillating component. Forexample, the I reference circuit generates a DC component to have amagnitude between 100 micro-amps and 300 micro-amps (or other range),generates a first sinusoidal oscillating current component at frequency1, and generates a second sinusoidal oscillating current component atfrequency 2. As a specific example, the first sinusoidal oscillatingcurrent component at frequency 1 is used to sense self-touch on a touchscreen display and the second sinusoidal oscillating current componentat frequency 2 is used to sense mutual touch on the touch screendisplay.

The regulated voltage source circuit 264 provides the regulated voltagesignal 266 to the sensor 30-1. When the sensor 30-1 is exposed to acondition 114-1, its impedance affects 240 the regulated voltage signal266 based on Z=V/I. As such, the sensor current 272 is created as aresult of the voltage (V) provided by the regulated voltage sourcecircuit 264 and the impedance of the sensor 30-1. As the impedance ofthe sensor 30-1 changes due to changing conditions 114-1, the voltageprovided by the regulated voltage source circuit 264 changes so that thesensor current 272 remains substantially equal to the current reference270, including the DC component and/or the oscillating component(s).

The voltage (V) loop correction circuit 262 is operable to generate acomparison signal 276 based on a comparison of the sensor current 272with the current reference 270. The effect of the impedance of thesensor on the regulated voltage signal 266 is detected by the V loopcorrection circuit 262 and is captured by the comparison signal 276. TheV loop correction circuit 262 is further operable to convert thecomparison signal 276 into the digital signal 202, which is a digitalrepresentation of the affect the impedance of the sensor has on theregulated voltage signal and corresponds to the sensed condition 114-1.The V loop correction circuit is further operable to convert the digitalsignal 202 into the analog regulation signal 274, thereby creating afeedback loop to keep the sensor current 272 substantially equal to thecurrent reference 270.

FIG. 28 is a schematic block diagram of another embodiment of a drivesense circuit 28-e 1 coupled to a variable impedance sensor 30-1. Thedrive sense circuit 28-e 1 includes a current (I) reference circuit260-1, a voltage (V) loop correction circuit 262-1, and a regulatedvoltage (V) source circuit 264-1. The I reference circuit 260-1 includesan independent current source to produce a reference current (I_(ref)).The V loop correction circuit 262-1 includes a current comparator (e.g.,a transimpedance amplifier), an analog to digital converter 212-4 and adigital to analog converter 214-4. The regulated voltage source 264-1includes a P-channel FET and a current mirror 273. The regulated voltagesource 264-1 may further include a bias circuit (not shown) coupledbetween the gate and source of the P-channel FET. The analog to digitalconverter 212-4 and the digital to analog converter 214-4 are one ormore of the types discussed with reference to FIG. 23.

When the drive sense circuit 28-e 1 is enabled, the regulated voltagesource circuit 264-1 is operable to generate a regulated voltage signal266 based on an analog regulation signal 274-1. The regulated voltagesource circuit 264 generates the regulated voltage signal 266 such thatthe sensor current 272 substantially matches the current reference 270,a multiple thereof, or a fraction thereof, produced by the I referencecircuit 260. The current mirror 273 mirrors the sensor current 272 andthe mirrored current substantially matches the current reference 270.The mirrored current produced by the current mirror 273 is equal to thesensor current 272, is greater than the sensor current 272, or is lessthan the sensor current 272 depending on the application and/or thesensor sensitivity.

The I reference circuit 260 (which may a DC current source and/or an ACcurrent source) generates the current reference 270-1 to include a DCcomponent and/or at least one oscillating component. For example, the Ireference circuit generates a DC component to have a magnitude between100 micro-amps and 300 micro-amps (or other range), generates a firstsinusoidal oscillating current component at frequency 1, and generates asecond sinusoidal oscillating current component at frequency 2.

The regulated voltage source circuit 264-1 provides the regulatedvoltage signal 266 to the sensor 30-1. When the sensor 30-1 is exposedto a condition 114-1, its impedance affects 240 the regulated voltagesignal 266 based on Z=V/I. As such, the sensor current 272 is created asa result of the voltage (V) provided by the regulated voltage sourcecircuit 264-1 and the impedance of the sensor 30-1. As the impedance ofthe sensor 30-1 changes due to changing conditions 114-1, the voltageprovided by the regulated voltage source circuit 264-1 changes so thatthe mirrored current of the sensor current 272 remains substantiallyequal to the current reference 270-1, including the DC component and/orthe oscillating component(s).

The current comparator (comp) compares the mirrored current of thesensor current 272 with the current reference 270-1 to generate thecomparison signal 276. The effect of the impedance of the sensor on theregulated voltage signal 266 is captured by the comparison signal 276.The analog to digital converter 212-4 converts the comparison signal 276into the digital signal 202, which is a digital representation of theaffect the impedance of the sensor has on the regulated voltage signaland corresponds to the sensed condition 114-1. The digital to analogconverter 214-4 convert the digital signal 202 into the analogregulation signal 274, thereby creating a feedback loop to keep themirrored current of the sensor current 272 substantially equal to thecurrent reference 270-1.

FIG. 29 is a schematic block diagram of another embodiment of a drivesense circuit 28-f coupled to a variable current sensor 30-2. The drivesense circuit 28-f includes an impedance (Z) reference circuit 280, avoltage (V) loop correction circuit 282, and a regulated voltage (V)source circuit 284. In general, the drive sense circuit 28-f regulatesthe voltage applied to the sensor and keeps the sensor's impedanceconstant to sense a current (I) of the sensor 30-2 in relation to asensor impedance 292 and an impedance (Z) reference 290. Varying currentof the sensor 30-2 is indicative of changes to the condition 114-2 beingsensed (e.g., magnetic field, current flow, etc.), which may be used inmotor monitoring applications, load sensing applications, electroniccircuit applications, failure analysis applications, etc.

When the drive sense circuit 28-f is enabled, the regulated voltagesource circuit 284 is operable to generate a regulated voltage signal286 based on an analog regulation signal 294. The regulated voltagesource circuit 284 generates the regulated voltage signal 286 such thatthe sensor impedance 292 (e.g., capacitance, inductance, etc.)substantially matches the impedance reference 290 produced by the Zreference circuit 280.

The Z reference circuit 280 (which may be a capacitor, an inductor, acircuit equivalent of a capacitor, a circuit equivalent of an inductor,a tunable capacitor bank, etc.) generates the impedance reference 290 toinclude a DC component and/or at least one oscillating (AC) component.For example, the Z reference circuit generates a DC component to have adesired resistance at DC and/or to have a first desired impedance atfrequency 1, and have a second desired impedance at frequency 2.

The regulated voltage source circuit 284 provides the regulated voltagesignal 286 to the sensor 30-2. When the sensor 30-2 is exposed to acondition 114-2, its current affects 288 the regulated voltage signal286 based on I=V/Z. As such, the sensor impedance 292 corresponds to thevoltage (V) provided by the regulated voltage source circuit 284 and thecurrent flowing through the sensor 30-2. As the current of the sensor30-2 changes due to changing conditions 114-1, the voltage provided bythe regulated voltage source circuit 284 changes so that the sensorimpedance 292 remains substantially equal to the impedance reference290, including the DC resistance and/or desired impedances at f1 and f2.

The voltage (V) loop correction circuit 282 is operable to generate acomparison signal 296 based on a comparison of the sensor impedance 292with the impedance reference 290. The effect of the current of thesensor on the regulated impedance signal 286 is detected by the V loopcorrection circuit 282 and is captured by the comparison signal 296. TheV loop correction circuit 282 is further operable to convert thecomparison signal 296 into the digital signal 202, which is a digitalrepresentation of the affect the current of the sensor has on theregulated voltage signal and corresponds to the sensed condition 114-2.The V loop correction circuit is further operable to convert the digitalsignal 202 into the analog regulation signal 294, thereby creating afeedback loop to keep the sensor impedance 292 substantially equal tothe impedance reference 290.

FIG. 30 is a schematic block diagram of another embodiment of a drivesense circuit 28-f 1 coupled to a variable current sensor 30-2. Thedrive sense circuit 28-f 1 includes an impedance (Z) reference circuit280-1, a voltage (V) loop correction circuit 282-1, and a regulatedvoltage (V) source circuit 284-1. The Z reference circuit includes acurrent source circuit and an impedance (Z_(ref)) The V loop correctioncircuit 282-1 includes a comparator (comp), an analog to digitalconverter 212-5 and a digital to analog converter 214-5. The analog todigital converter 212-5 and the digital to analog converter 214-5 areone or more of the types discussed with reference to FIG. 23.

When the drive sense circuit 28-f 1 is enabled, the regulated voltagesource circuit 284-1, which includes a P-channel transistor and avoltage bias circuit, is operable to generate a regulated voltage signal286 based on an analog regulation signal 294. The regulated voltagesource circuit 284-1 generates the regulated voltage signal 286 suchthat the sensor impedance 292 (e.g., capacitance, inductance, etc.)substantially matches the impedance reference 290 produced by the Zreference circuit 280.

The Z reference circuit 280 (which includes a current source circuit andan impedance) generates the impedance reference 290 in accordance with(V/I) to include a DC component and/or at least one oscillating (AC)component. For example, the Z reference circuit generates a DC componentto have a desired resistance at DC, to have a first desired impedance atfrequency 1, and to have a second desired impedance at frequency 2.

The regulated voltage source circuit 284-1 provides the regulatedvoltage signal 286 to the sensor 30-2. When the sensor 30-2 is exposedto a condition 114-2, its current affects 288 the regulated impedancesignal 286 based on I=V/Z. As such, the sensor impedance 292 correspondsto the voltage (V) provided by the regulated voltage source circuit 284and the current flowing through the sensor 30-2. As the current of thesensor 30-2 changes due to changing conditions 114-1, the voltageprovided by the regulated voltage source circuit 284 changes so that thesensor impedance 292 remains substantially equal to the impedancereference 290, including the DC resistance and/or desired impedances atf1 and f2.

The comparator compares (as voltages or currents) the impedancereference with the sensor impedance 292 to produce a comparison signal296, which captures the effect of the current of the sensor has on theregulated impedance signal 286. The analog to digital converter 212-5converts the comparison signal 296 into the digital signal 202, which isa digital representation of the affect the current of the sensor has onthe regulated voltage signal and corresponds to the sensed condition114-2. The digital to analog converter 214-5 converts the digital signal202 into the analog regulation signal 294, thereby creating a feedbackloop to keep the sensor impedance 292 substantially equal to theimpedance reference 290.

FIG. 30A is a schematic block diagram of another embodiment of a drivesense circuit 28-f 2 coupled to a variable current sensor 30-2. Thedrive sense circuit 28-f 2 includes an impedance (Z) reference circuit280-1, a voltage (V) loop correction circuit 282-1 a, and a regulatedvoltage (V) source circuit 284-1. The Z reference circuit 280-1 includesa current source circuit and an impedance (Z_(ref)) The V loopcorrection circuit 282-1 a includes a comparator (comp) and an analog todigital converter 212-5 a. The analog to digital converter 212-5 a isone or more of the types discussed with reference to FIG. 23.

When the drive-sense circuit 28-f 2 is enabled, the regulated voltagesource circuit 284-1, which includes a P-channel transistor and avoltage bias circuit, is operable to generate a regulated voltage signal286 based on comparison signal 296-1. The regulated voltage sourcecircuit 284-1 generates the regulated voltage signal 286 such that thesensor impedance 292 (e.g., capacitance, inductance, etc.) substantiallymatches the impedance reference 290 produced by the Z reference circuit280-1.

The Z reference circuit 280-1 (which includes a current source circuitand an impedance) generates the impedance reference 290 in accordancewith (V/I) to include a DC component and/or at least one oscillating(AC) component. For example, the Z reference circuit generates a DCcomponent to have a desired resistance at DC, to have a first desiredimpedance at frequency 1, and to have a second desired impedance atfrequency 2.

The regulated voltage source circuit 284-1 provides the regulatedvoltage signal 286 to the variable current sensor 30-2. When thevariable current sensor 30-2 is exposed to a condition 114-2, itscurrent affects 288 the regulated voltage signal 286 based on I=V/Z. Assuch, the sensor impedance 292 corresponds to the voltage (V) providedby the regulated voltage source circuit 284-1 and the current flowingthrough the sensor 30-2. As the current of the sensor 30-2 changes dueto changing conditions 114-2, the voltage provided by the regulatedvoltage source circuit 284 changes so that the sensor impedance 292remains substantially equal to the impedance reference 290, includingthe DC resistance and/or desired impedances at f1 and f2.

The comparator compares (as voltages or currents) the impedancereference 290 with the sensor impedance 292 to produce a comparisonsignal 296-1, which captures the effect of the current of the sensor hason the regulated impedance signal 286. The comparison signal 296-1 isprovided to the voltage bias circuit, thereby creating a feedback loopto keep the sensor impedance 292 substantially equal to the impedancereference 290. The analog to digital converter 212-5 a converts thecomparison signal 296 into the digital signal 202, which is a digitalrepresentation of the affect the current of the sensor has on theregulated voltage signal 286 and corresponds to the sensed condition114-2.

FIG. 31 is a schematic block diagram of another embodiment of a drivesense circuit 28-g coupled to a variable current sensor 30-2. The drivesense circuit 28-g includes a voltage (V) reference circuit 300, animpedance (Z) loop correction circuit 302, and a regulated impedance (Z)source circuit 304. In general, the drive sense circuit 28-g regulatesthe impedance of the sensor and keeps the sensor's voltage constant tosense a current (I) of the sensor 30-2 in relation to a sensor voltage306 and a voltage (V) reference 312. Varying current of the sensor 30-2is indicative of changes to the condition 114-2 being sensed (e.g.,magnetic field, current flow, etc.), which may be used in motormonitoring applications, load sensing applications, electronic circuitapplications, failure analysis applications, etc.

When the drive sense circuit 28-g is enabled, the regulated impedancesource circuit 304 is operable to generate a regulated impedance signal308 based on an analog regulation signal 314. The regulated impedancesource circuit 304 generates the regulated impedance signal 308 byvarying frequency of a voltage produced by the regulated Z sourcecircuit 304 such that the sensor voltage 306 substantially matches thevoltage reference 312 produced by the V reference circuit 300.

The V reference circuit 300 (which includes a bandgap reference, alinear regulator, a power supply, a divider network, an AC generator, acombining circuit and/or etc.) generates the voltage reference 312 toinclude a DC component and/or at least one oscillating (AC) component.For example, the V reference circuit generates a DC component to have adesired DC level, a first oscillating component at a first frequency 1,and a second oscillating component at frequency 2. Alternatively, thefrequency of the oscillating component sweeps a frequency range to finda frequency, or frequencies, that optimizes the impedance of the sensor.

The regulated impedance source circuit 304 provides the regulatedimpedance signal 308 to the sensor 30-2. When the sensor 30-2 is exposedto a condition 114-2, its current affects 288 the regulated impedancesignal 308 based on I=V/Z. As such, the sensor voltage 306 correspondsto the impedance of the sensor as regulated by the regulation Z sourcecircuit and the current provided by the regulated impedance sourcecircuit 304 to the sensor 30-2. As the current of the sensor 30-2changes due to changing conditions 114-2, the impedance is adjusted bythe regulated impedance source circuit 304 changes so that the sensorvoltage 306 remains substantially equal to the voltage reference 312,including the DC resistance and desired impedances at f1 and f2.

The impedance (Z) loop correction circuit 302 is operable to generate acomparison signal 316 based on a comparison of the sensor voltage 306with the voltage reference 312. The effect of the current of the sensoron the regulated voltage signal 308 is detected by the Z loop correctioncircuit 302 and is captured by the comparison signal 316. The Z loopcorrection circuit 302 is further operable to convert the comparisonsignal 316 into the digital signal 202, which is a digitalrepresentation of the affect the current of the sensor has on theregulated impedance signal and corresponds to the sensed condition114-2. The Z loop correction circuit is further operable to convert thedigital signal 202 into the analog regulation signal 314, therebycreating a feedback loop to keep the sensor voltage 306 substantiallyequal to the voltage reference 312.

FIG. 32 is a schematic block diagram of another embodiment of a drivesense circuit 28-g 1 coupled to a variable current sensor 30-2. Thedrive sense circuit 28-g 1 includes a voltage (V) reference circuit300-1, an impedance (Z) loop correction circuit 302-1, and a regulatedimpedance (Z) source circuit 304. The voltage reference circuit 300-1includes a current source circuit 320 and a variable impedance. The Zloop correction circuit 302-1 includes a comparator or op amp, an analogto digital converter 212-6 and a digital to analog converter 214-6. Theanalog to digital converter 212-6 and the digital to analog converter214-6 are one or more of the types discussed with reference to FIG. 23.

When the drive sense circuit 28-g 1 is enabled, the regulated impedancesource circuit 304-1 is operable to generate the regulated impedancesignal 308 based on an analog regulation signal 314. The frequencyvariable bias circuit 324 provides a frequency vary gate source voltageto the P-channel FET to generate the regulated impedance signal 308,which includes a varying frequency voltage component. In this manner,the sensor voltage 306 substantially matches the voltage reference 312produced by the V reference circuit 300-1.

The V reference circuit 300 (which includes a current source and avariable impedance.) generates the voltage reference 312 to include a DCcomponent and/or at least one oscillating (AC) component. For example,the current source circuit 320 and/or the variable impedance generate aDC component to have a desired DC level, a first oscillating componentat a first frequency 1, and a second oscillating component at frequency2. Alternatively, the current source circuit 320 and/or the variableimpedance performs a frequency sweeps within a frequency range to find afrequency, frequencies, that optimizes the impedance of the sensor.

The regulated impedance source circuit 304 provides the regulatedimpedance signal 308 to the sensor 30-2. When the sensor 30-2 is exposedto a condition 114-2, its current affects 288 the regulated impedancesignal 308 based on I=V/Z. As such, the sensor voltage 306 correspondsto the impedance of the sensor as regulated by the regulation Z sourcecircuit and the current provided by the regulated impedance sourcecircuit 304 to the sensor 30-2. As the current of the sensor 30-2changes due to changing conditions 114-2, the impedance is adjusted bythe regulated impedance source circuit 304 changes so that the sensorvoltage 306 remains substantially equal to the voltage reference 312,including the DC resistance and/or desired impedances at f1 and f2.

The comparator is operable to generate a comparison signal 316 based ona comparison of the sensor voltage 306 with the voltage reference 312.The effect of the current of the sensor on the regulated voltage signal308 is detected by the Z loop correction circuit 302 and is captured bythe comparison signal 316. The analog to digital converter 212-6converts the comparison signal 316 into the digital signal 202, which isa digital representation of the affect the current of the sensor has onthe regulated impedance signal and corresponds to the sensed condition114-2. The digital to analog converter 214-6 convert the digital signal202 into the analog regulation signal 314, thereby creating a feedbackloop to keep the sensor voltage 306 substantially equal to the voltagereference 312.

FIG. 33 is a schematic block diagram of another embodiment of a drivesense circuit 28-g 2 coupled to a variable current sensor 30-2. Thedrive sense circuit 28-g 1 includes a voltage (V) reference circuit(which includes a current source and an impedance (Zref)), an impedance(Z) loop correction circuit (which includes the comparator, the analogto digital converter 212-6, the digital to analog converter 214-6, acurrent mirror circuit 322, and a controlled variable impedance 318),and a regulated impedance (Z) source circuit (which includes a voltagebias circuit 324 and a P-channel FET).

When the drive sense circuit 28-g 1 is enabled, the comparator comparesthe voltage reference signal 312 with the sensor voltage 306 to producethe comparison signal. The analog to digital converter converts thecomparison signal into the digital signal 202. The digital to analogconverter converts the digital signal 202 into the analog regulationsignal 314.

The analog regulation signal 314 varies the impedance of the controlledvariable impedance 318. The varying impedance of circuit 318 ismultiplied by the mirrored current (Im) of the sensor current (Is) toproduce the sensor voltage 306. The mirrored current is produced by thecurrent mirror circuit 322 that mirrors the current provided by theP-channel FET to the variable current sensor 30-2. The P-channel FET isenabled via the voltage bias circuit 324, which includes one or moreresistors and/or one or more capacitors. The varying of the impedance ofthe controlled variable impedance 318 regulates the sensor voltage 306to substantially match the reference voltage 312.

FIG. 34 is a schematic block diagram of another embodiment of a drivesense circuit 28-h coupled to a variable voltage sensor 30-3. The drivesense circuit 28-h includes a current (I) reference circuit 330, animpedance (Z) loop correction circuit 332, and a regulated impedance (Z)source circuit 334. In general, the drive sense circuit 28-h regulatesthe impedance of the sensor and keeps the sensor's current constant tosense a voltage (V) of the sensor 30-3 in relation to a sensor current336 and a current (I) reference 342. Varying voltage of the sensor 30-3is indicative of changes to the condition 114-3 being sensed (e.g.,voltage levels, capacitance, inductance, thermal conditions, etc.).

When the drive sense circuit 28-h is enabled, the regulated impedancesource circuit 334 is operable to generate a regulated impedance signal338 based on an analog regulation signal 344. The regulated impedancesource circuit 334 generates the regulated impedance signal 338 byvarying frequency of a current produced by the regulated Z sourcecircuit 334 such that the sensor current 306 substantially matches thevoltage reference 342 produced by the I reference circuit 330.

The I reference circuit 330 (which may be implement in accordance with apreviously discussed current reference circuit) generates the currentreference 342 to include a DC component and/or at least one oscillating(AC) component. For example, the I reference circuit generates a DCcomponent to have a desired DC level, a first oscillating component at afirst frequency 1, and a second oscillating component at frequency 2.Alternatively, the frequency of the oscillating component sweeps afrequency range to find a frequency, or frequencies, that optimizes theimpedance of the sensor.

The regulated impedance source circuit 334 provides the regulatedimpedance signal 338 to the sensor 30-3. When the sensor 30-3 is exposedto a condition 114-3, its voltage affects 288 the regulated impedancesignal 338 based on V=I*Z. As such, the sensor current 336 correspondsto the impedance of the sensor as regulated by the regulation Z sourcecircuit and the voltage provided by the regulated impedance sourcecircuit 334 to the sensor 30-3. As the voltage of the sensor 30-3changes due to changing conditions 114-3, the impedance is adjusted bythe regulated impedance source circuit 334 so that the sensor current336 remains substantially equal to the current reference 342, includingthe DC resistance and/or desired impedances at f1 and f2.

The impedance (Z) loop correction circuit 332 is operable to generate acomparison signal 346 based on a comparison of the sensor current 336with the current reference 342. The effect of the voltage of the sensoron the regulated impedance signal 338 is detected by the Z loopcorrection circuit 332 and is captured by the comparison signal 336. TheZ loop correction circuit 332 is further operable to convert thecomparison signal 336 into the digital signal 202, which is a digitalrepresentation of the affect the voltage of the sensor has on theregulated impedance signal and corresponds to the sensed condition114-3. The Z loop correction circuit is further operable to convert thedigital signal 202 into the analog regulation signal 344, therebycreating a feedback loop to keep the sensor current 336 substantiallyequal to the current reference 342.

FIG. 35 is a schematic block diagram of another embodiment of a drivesense circuit 28-h 1 coupled to a variable voltage sensor 30-3. Thedrive sense circuit 28-h 1 includes a current (I) reference circuit 330,an impedance (Z) loop correction circuit 332, and a regulated impedance(Z) source circuit 334. The I reference circuit 330 includes a variablecurrent source circuit 350. The Z loop correction circuit 332 includes acomparator, an analog to digital converter 212-8 and a digital to analogconverter 214-8. The regulated Z source circuit 334 includes a variableimpedance 354, a P-channel FET, and a voltage bias circuit 352. Theanalog to digital converter 212-8 and the digital to analog converter214-8 are one or more of the types discussed with reference to FIG. 23.

The voltage bias circuit 352 generates a gate-source voltage for theP-channel FET and the impedance of the variable impedance is adjustedbased on the analog regulation signal 344. In this embodiment, thecombination of the variable impedance and P-channel transistor generatea regulated impedance signal 338 at a desired current level for thevariable voltage sensor 30-3. The regulated impedance signal 338 isregulated to obtain a desired impedance of the sensor 30-3 such that, atthe desired current level (e.g., a few micro amps to an amp or more),variation of the voltage of the sensor is within the linear range of thesensor.

The I reference circuit 330 (which may be implement in accordance with apreviously discussed current reference circuit) generates the currentreference 342 to include a DC component and/or at least one oscillating(AC) component. For example, the variable current source circuit 350generates a DC component to have a desired DC level, a first oscillatingcomponent at a first frequency 1, and a second oscillating component atfrequency 2.

The comparator (e.g., a transimpedance amplifier) compares the sensorcurrent 336 with the current reference 342 to produce the comparisonsignal 346. The effect of the voltage of the sensor on the regulatedimpedance signal 338 is captured by the comparison signal 336. Theanalog to digital converter 212-8 converts the comparison signal 346into the digital signal 202, which is a digital representation of theaffect the voltage of the sensor has on the regulated impedance signaland corresponds to the sensed condition 114-3. The digital to analogconverter converts the digital signal 202 into the analog regulationsignal 344, thereby creating a feedback loop to keep the sensor current336 substantially equal to the current reference 342.

FIG. 36 is a schematic block diagram of another embodiment of a drivesense circuit 28-h 2 is coupled to a variable voltage sensor 30-3. Thedrive sense circuit 28-h 2 includes a P-channel transistor 335, avariable impedance 333 (e.g., resistor(s), capacitor(s), and/ortransistor(s)), a comparator 331, the analog to digital converter 212-8,and the digital to analog converter 214-8.

In operation, the variable voltage sensor 30-3 is exposed to a conditionthat changes its voltage when its receiving the variable impedancesignal at a current level (Is). The comparator 331 compares a mirroredcurrent of the sensor 30-1 with the current reference 342 to produce thecomparison signal 336. The analog to digital converter 212-8 convertsthe comparison signal 336 into the digital signal 202. The digital toanalog converter 214-8 convers the digital signal 202 into the analogregulation signal 344. The variable impedance 333 is adjusted based onthe analog regulation signal 334. Adjusting the variable impedance 333adjusts the gate-source voltage of the P-channel transistor to producethe regulated impedance signal 338.

FIG. 37 is a schematic block diagram of another embodiment of a drivesense circuit 28-i coupled to a variable voltage sensor 30-3. The drivesense circuit 28-i includes an impedance (Z) reference circuit 360, acurrent (I) loop correction circuit 262, and a regulated current (I)source circuit 264. In general, the drive sense circuit 28-i regulatesthe current applied to the sensor and keeps the impedance of sensorconstant to sense a voltage of the sensor 30-3 in relation to a sensorimpedance 366 and an impedance reference 372.

When the drive sense circuit 28-i is enabled, the regulated currentsource circuit 364 is operable to generate a regulated current signal368 based on an analog regulation signal 374. The regulated currentsource circuit 364 generates the regulated current signal 368 such thatthe sensor impedance (Z) 366 substantially matches the impedancereference 372 produced by the Z reference circuit 260.

The Z reference circuit 360 (which may be a capacitor, an inductor, acircuit equivalent of a capacitor, a circuit equivalent of an inductor,a tunable capacitor bank, etc.) generates the impedance reference 372 toinclude a DC component and/or at least one oscillating component. Forexample, the impedance reference 372 includes a DC component and/or atleast one oscillating (AC) component. For example, the Z referencecircuit 360 generates a DC component to have a desired resistance at DC,a first desired impedance at frequency 1, and a second desired impedanceat frequency 2.

The regulated current source circuit 364 provides the regulated currentsignal 368 to the sensor 30-3. When the sensor 30-3 is exposed to acondition 114-3, its voltage affects 370 the regulated current signal388 based on I=V/Z. As such, the sensor impedance 366 is created as aresult of the current (I) provided by the regulated current sourcecircuit 364 and the voltage of the sensor 30-3. As the voltage of thesensor 30-3 changes due to changing conditions 114-3, the currentprovided by the regulated current source circuit 234 changes so that thesensor impedance 366 remains substantially equal to the impedancereference 372, including the DC component and/or the oscillatingcomponent(s).

The current (I) loop correction circuit 362 is operable to generate acomparison signal 376 based on a comparison of the sensor impedance 366with the impedance reference 372. The effect of the voltage of thesensor on the regulated current signal 368 is detected by the I loopcorrection circuit 362 and captured by the comparison signal 376. The Iloop correction circuit 362 is further operable to convert thecomparison signal 376 into a digital signal 202, which is a digitalrepresentation of the affect the voltage of the sensor has on theregulated current signal and corresponds to the sensed condition 114-3.The I loop correction circuit is further operable to convert the digitalsignal 202 into the analog regulation signal 374, thereby creating afeedback loop to keep the sensor impedance 366 substantially equal tothe impedance reference 372.

FIG. 38 is a schematic block diagram of another embodiment of a drivesense circuit 28-i 1 coupled to a variable voltage sensor 30-3. Thedrive sense circuit 28-i 1 includes an impedance (Z) reference circuit360-1, a current (I) loop correction circuit 262-1, and a regulatedcurrent (I) source circuit 364-1, implemented as a dependent currentsource. The Z reference circuit 360-1 includes a current source circuitand an impedance circuit (e.g., resistor(s), capacitor(s), inductor(s),transistor(s), etc.) to produce the impedance reference, which may beexpressed as a voltage (V of impedance reference=current of currentsource times impedance of the impedance circuit).

The dependent current source 364-1 generate a regulated current signal368 based on the analog regulation signal 374. The voltage of the sensor30 and current of the regulated current signal 368 provides the sensorimpedance 366.

The comparator compares the sensor impedance 366 with the impedancereference, which may be done in voltage, to produce the comparisonsignal 376. The analog to digital converter 212-8 converts thecomparison signal 376 into a digital signal 202, which is a digitalrepresentation of the affect the voltage of the sensor has on theregulated current signal and corresponds to the sensed condition 114-3.The digital to analog converter 214-8 converts the digital signal 202into the analog regulation signal 374, thereby creating a feedback loopto keep the sensor impedance 366 substantially equal to the impedancereference 372.

As used in the preceding figures, a drive sense circuit has the generalreference number of 28. When, in a particular figure, the drive sensecircuit's reference number has a suffix (e.g., -a, -b, -c, etc.), thereference number with a suffix is referring to a specific embodiment ofa drive sense circuit. A specific embodiment of a drive sense circuitincludes some or all of the features and/or functions of drive sensecircuits having no suffix to its reference number. Further, when a drivesense circuit has a suffix with a letter and a number, this isrepresented of different sub-embodiments of an embodiment of the drivesense circuit. The same applies for other components in the figures thathave a reference number with a suffix.

It is noted that terminologies as may be used herein such as bit stream,stream, signal sequence, etc. (or their equivalents) have been usedinterchangeably to describe digital information whose contentcorresponds to any of a number of desired types (e.g., data, video,speech, text, graphics, audio, etc. any of which may generally bereferred to as ‘data’).

As may be used herein, the terms “substantially” and “approximately”provide an industry-accepted tolerance for its corresponding term and/orrelativity between items. For some industries, an industry-acceptedtolerance is less than one percent and, for other industries, theindustry-accepted tolerance is 10 percent or more. Other examples ofindustry-accepted tolerance range from less than one percent to fiftypercent. Industry-accepted tolerances correspond to, but are not limitedto, component values, integrated circuit process variations, temperaturevariations, rise and fall times, thermal noise, dimensions, signalingerrors, dropped packets, temperatures, pressures, material compositions,and/or performance metrics. Within an industry, tolerance variances ofaccepted tolerances may be more or less than a percentage level (e.g.,dimension tolerance of less than +/−1%). Some relativity between itemsmay range from a difference of less than a percentage level to a fewpercent. Other relativity between items may range from a difference of afew percent to magnitude of differences.

As may also be used herein, the term(s) “configured to”, “operablycoupled to”, “coupled to”, and/or “coupling” includes direct couplingbetween items and/or indirect coupling between items via an interveningitem (e.g., an item includes, but is not limited to, a component, anelement, a circuit, and/or a module) where, for an example of indirectcoupling, the intervening item does not modify the information of asignal but may adjust its current level, voltage level, and/or powerlevel. As may further be used herein, inferred coupling (i.e., where oneelement is coupled to another element by inference) includes direct andindirect coupling between two items in the same manner as “coupled to”.

As may even further be used herein, the term “configured to”, “operableto”, “coupled to”, or “operably coupled to” indicates that an itemincludes one or more of power connections, input(s), output(s), etc., toperform, when activated, one or more its corresponding functions and mayfurther include inferred coupling to one or more other items. As maystill further be used herein, the term “associated with”, includesdirect and/or indirect coupling of separate items and/or one item beingembedded within another item.

As may be used herein, the term “compares favorably”, indicates that acomparison between two or more items, signals, etc., provides a desiredrelationship. For example, when the desired relationship is that signal1 has a greater magnitude than signal 2, a favorable comparison may beachieved when the magnitude of signal 1 is greater than that of signal 2or when the magnitude of signal 2 is less than that of signal 1. As maybe used herein, the term “compares unfavorably”, indicates that acomparison between two or more items, signals, etc., fails to providethe desired relationship.

As may be used herein, one or more claims may include, in a specificform of this generic form, the phrase “at least one of a, b, and c” orof this generic form “at least one of a, b, or c”, with more or lesselements than “a”, “b”, and “c”. In either phrasing, the phrases are tobe interpreted identically. In particular, “at least one of a, b, and c”is equivalent to “at least one of a, b, or c” and shall mean a, b,and/or c. As an example, it means: “a” only, “b” only, “c” only, “a” and“b”, “a” and “c”, “b” and “c”, and/or “a”, “b”, and “c”.

As may also be used herein, the terms “processing module”, “processingcircuit”, “processor”, “processing circuitry”, and/or “processing unit”may be a single processing device or a plurality of processing devices.Such a processing device may be a microprocessor, micro-controller,digital signal processor, microcomputer, central processing unit, fieldprogrammable gate array, programmable logic device, state machine, logiccircuitry, analog circuitry, digital circuitry, and/or any device thatmanipulates signals (analog and/or digital) based on hard coding of thecircuitry and/or operational instructions. The processing module,module, processing circuit, processing circuitry, and/or processing unitmay be, or further include, memory and/or an integrated memory element,which may be a single memory device, a plurality of memory devices,and/or embedded circuitry of another processing module, module,processing circuit, processing circuitry, and/or processing unit. Such amemory device may be a read-only memory, random access memory, volatilememory, non-volatile memory, static memory, dynamic memory, flashmemory, cache memory, and/or any device that stores digital information.Note that if the processing module, module, processing circuit,processing circuitry, and/or processing unit includes more than oneprocessing device, the processing devices may be centrally located(e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that if the processing module, module, processing circuit,processing circuitry and/or processing unit implements one or more ofits functions via a state machine, analog circuitry, digital circuitry,and/or logic circuitry, the memory and/or memory element storing thecorresponding operational instructions may be embedded within, orexternal to, the circuitry comprising the state machine, analogcircuitry, digital circuitry, and/or logic circuitry. Still further notethat, the memory element may store, and the processing module, module,processing circuit, processing circuitry and/or processing unitexecutes, hard coded and/or operational instructions corresponding to atleast some of the steps and/or functions illustrated in one or more ofthe Figures. Such a memory device or memory element can be included inan article of manufacture.

One or more embodiments have been described above with the aid of methodsteps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claims. Further, the boundariesof these functional building blocks have been arbitrarily defined forconvenience of description. Alternate boundaries could be defined aslong as the certain significant functions are appropriately performed.Similarly, flow diagram blocks may also have been arbitrarily definedherein to illustrate certain significant functionality.

To the extent used, the flow diagram block boundaries and sequence couldhave been defined otherwise and still perform the certain significantfunctionality. Such alternate definitions of both functional buildingblocks and flow diagram blocks and sequences are thus within the scopeand spirit of the claims. One of average skill in the art will alsorecognize that the functional building blocks, and other illustrativeblocks, modules and components herein, can be implemented as illustratedor by discrete components, application specific integrated circuits,processors executing appropriate software and the like or anycombination thereof.

In addition, a flow diagram may include a “start” and/or “continue”indication. The “start” and “continue” indications reflect that thesteps presented can optionally be incorporated in or otherwise used inconjunction with one or more other routines. In addition, a flow diagrammay include an “end” and/or “continue” indication. The “end” and/or“continue” indications reflect that the steps presented can end asdescribed and shown or optionally be incorporated in or otherwise usedin conjunction with one or more other routines. In this context, “start”indicates the beginning of the first step presented and may be precededby other activities not specifically shown. Further, the “continue”indication reflects that the steps presented may be performed multipletimes and/or may be succeeded by other activities not specificallyshown. Further, while a flow diagram indicates a particular ordering ofsteps, other orderings are likewise possible provided that theprinciples of causality are maintained.

The one or more embodiments are used herein to illustrate one or moreaspects, one or more features, one or more concepts, and/or one or moreexamples. A physical embodiment of an apparatus, an article ofmanufacture, a machine, and/or of a process may include one or more ofthe aspects, features, concepts, examples, etc. described with referenceto one or more of the embodiments discussed herein. Further, from figureto figure, the embodiments may incorporate the same or similarly namedfunctions, steps, modules, etc. that may use the same or differentreference numbers and, as such, the functions, steps, modules, etc. maybe the same or similar functions, steps, modules, etc. or differentones.

While the transistors in the above described figure(s) is/are shown asfield effect transistors (FETs), as one of ordinary skill in the artwill appreciate, the transistors may be implemented using any type oftransistor structure including, but not limited to, bipolar, metal oxidesemiconductor field effect transistors (MOSFET), N-well transistors,P-well transistors, enhancement mode, depletion mode, and zero voltagethreshold (VT) transistors.

Unless specifically stated to the contra, signals to, from, and/orbetween elements in a figure of any of the figures presented herein maybe analog or digital, continuous time or discrete time, and single-endedor differential. For instance, if a signal path is shown as asingle-ended path, it also represents a differential signal path.Similarly, if a signal path is shown as a differential path, it alsorepresents a single-ended signal path. While one or more particulararchitectures are described herein, other architectures can likewise beimplemented that use one or more data buses not expressly shown, directconnectivity between elements, and/or indirect coupling between otherelements as recognized by one of average skill in the art.

The term “module” is used in the description of one or more of theembodiments. A module implements one or more functions via a device suchas a processor or other processing device or other hardware that mayinclude or operate in association with a memory that stores operationalinstructions. A module may operate independently and/or in conjunctionwith software and/or firmware. As also used herein, a module may containone or more sub-modules, each of which may be one or more modules.

As may further be used herein, a computer readable memory includes oneor more memory elements. A memory element may be a separate memorydevice, multiple memory devices, or a set of memory locations within amemory device. Such a memory device may be a read-only memory, randomaccess memory, volatile memory, non-volatile memory, static memory,dynamic memory, flash memory, cache memory, and/or any device thatstores digital information. The memory device may be in a form asolid-state memory, a hard drive memory, cloud memory, thumb drive,server memory, computing device memory, and/or other physical medium forstoring digital information.

While particular combinations of various functions and features of theone or more embodiments have been expressly described herein, othercombinations of these features and functions are likewise possible. Thepresent disclosure is not limited by the particular examples disclosedherein and expressly incorporates these other combinations.

What is claimed is:
 1. A drive-sense circuit configured to drive andsimultaneously sense a variable impedance load via a single line,wherein the drive-sense circuit comprises: a voltage reference circuitoperable to: generate a voltage reference signal having one or moreoscillating components, wherein a first oscillating component of the oneor more oscillating components oscillates at a first frequency; aregulated current source circuit operable to: generate a regulatedcurrent signal based on an analog regulation signal, wherein theregulated current signal is provided on the single line to the variableimpedance load to keep a load voltage on the line substantially matchingthe voltage reference signal, wherein when the load is exposed to afirst condition, an impedance of the variable impedance load changes,and wherein the impedance change affects the regulated current signal;and a current loop correction circuit operable to: generate a comparisonsignal based on the voltage reference signal and the load voltage,wherein the comparison signal represents the impedance change, andwherein the analog regulation signal is representative of the comparisonsignal; and convert the comparison signal into a digital signal, whereinthe digital signal is a digital representation of the impedance changeof the variable impedance load.
 2. The drive-sense circuit of claim 1,wherein the current loop correction circuit further comprises: an analogto digital converter circuit operable to produce the digital signalbased on the comparison signal, wherein the digital signal furthercorresponds to the first condition.
 3. The drive-sense circuit of claim2, wherein the current loop correction circuit further comprises: adigital to analog circuit operable to produce the analog regulationsignal based on the digital signal.
 4. The drive-sense circuit of claim1, wherein the current loop correction circuit is further operable to:when the variable impedance load is exposed to a second condition thatcreates a second impedance change of the variable impedance load,generate a second comparison signal that represents the affect of thesecond impedance change on the regulated current signal.
 5. Thedrive-sense circuit of claim 1, wherein the voltage reference signalfurther includes a direct current (DC) component.
 6. The drive-sensecircuit of claim 5, wherein the variable impedance load is a touchsensor, and wherein the first frequency is utilized to sense aself-touch of the touch sensor.
 7. The drive-sense circuit of claim 6,wherein a second oscillating component of the one or more oscillatingcomponents oscillates at a second frequency, and wherein the secondfrequency is utilized to detect a mutual touch of the touch sensor. 8.The drive-sense circuit of claim 1, wherein the current loop correctioncircuit comprises: an operational amplifier; an analog to digitalconverter; and a digital to analog converter.
 9. The drive-sense circuitof claim 1, wherein the voltage reference circuit comprises one or moreof: a bandgap reference circuit; a regulator; a divider network; analternating current (AC) generator; and a combining circuit.
 10. Adrive-sense circuit configured to drive and simultaneously sense avariable impedance load via a single line, wherein the drive-sensecircuit comprises: a current reference circuit operable to: generate acurrent reference signal having one or more oscillating components,wherein a first oscillating component of the one or more oscillatingcomponents oscillates at a first frequency; a regulated voltage sourcecircuit operable to: generate a regulated voltage signal based on ananalog regulation signal, wherein the regulated voltage signal isprovided on the single line to the variable impedance load to keep aload current on the line substantially matching the current referencesignal, wherein when the load is exposed to a first condition, animpedance of the variable impedance load changes, and wherein theimpedance change affects the regulated voltage signal; and a voltageloop correction circuit operable to: generate a comparison signal basedon the current reference signal and the load current, wherein thecomparison signal represents the impedance change, and wherein theanalog regulation signal is representative of the comparison signal; andconvert the comparison signal into a digital signal, wherein the digitalsignal is a digital representation of the impedance change of thevariable impedance load.
 11. The drive-sense circuit of claim 10,wherein the voltage loop correction circuit further comprises: an analogto digital converter circuit operable to produce the digital signalbased on the comparison signal, wherein the digital signal furthercorresponds to the first condition.
 12. The drive-sense circuit of claim11, wherein the voltage loop correction circuit further comprises: adigital to analog circuit operable to produce the analog regulationsignal based on the digital signal.
 13. The drive-sense circuit of claim10, wherein the voltage loop correction circuit is further operable to:when the variable impedance load is exposed to a second condition thatcreates a second impedance change of the variable impedance load,generate a second comparison signal that represents the affect of thesecond impedance change on the regulated voltage signal.
 14. Thedrive-sense circuit of claim 10, wherein the current reference signalfurther includes a direct current (DC) component.
 15. The drive-sensecircuit of claim 14, wherein the variable impedance load is a touchsensor and wherein the first frequency is utilized to sense a self-touchof the touch sensor.
 16. The drive-sense circuit of claim 15, wherein asecond oscillating component of the one or more oscillating componentsoscillates at a second frequency, and wherein the second frequency isutilized to detect a mutual touch of the touch sensor.
 17. Thedrive-sense circuit of claim 10, wherein the voltage loop correctioncircuit comprises: an operational amplifier; an analog to digitalconverter; and a digital to analog converter.
 18. The drive-sensecircuit of claim 10, wherein the current reference circuit comprises oneor more of: a biased dependent current source; an independent currentsource; a current mirror; an alternating current (AC) generator; and acombining circuit.